Are you on any type of medication or supplements? 

I second medications .. and supplements that seem to be fine for everyone else seem to cause all kinds of reactions for me.  If this is the second time, can you piece it together with what you've eaten?  Or was your environment unique each of these two times?  You could allergic to food, meds, mold in the fall air, bites from insects/bugs, etc., etc.  I'd get some advice on what to take, sounds like these are reasonably serious allergic reactions!

I might also mentioned that I took Flagyl for quite a while and it took months, but all of a sudden I developed allergic reactions.  Sometimes it takes a while, rather than have them happen immediately.

I don't think it's medications, etc. I'm only on One A Day Vitamins (no niacin) and I take Imodium. I've been taking both these for five years now with zero side effects. This is different because it only hits me while I'm sleeping and it comes on rapidly. I hadn't eaten since 8:30 pm and yet I woke up at 1 am with the first symptoms. From there, it came on fast and within 10 minutes, hives everywhere and severe itching and three trips to the restroom with runs. Then just as fast as it came on, it starts to fade. My prior attack was exactly the same.

That's crazy sounding. Have you started eating a particular food that you haven't been? Whatever the cause, you need to tell your doctor about these episodes. hope you get it figured out. 

Deathstalker,

I have had some crazy alergic reactions...Some almost as weird as yours.

I ended up getting tested...although they found the usual suspects (pollens, grains etc) they also discovered a sulphite (sp?) reaction...Severe in most cases.

What the alergologist explained to me was that a reaction is a reaction...they can start out mild like the redding of cheeks, a bit of itchies or a runny nose but then as time goes by and you re-expose yourself to the alergenes your body ramps up its reactions.

I ended up having anaphlaxia with a sip of white wine (they use sulphur to clean out the wine casks here). A year later it was greenbeans in a restaurant (they use a sulphur derivative to conserve certain canned veggies) and yet another time it was a totally unknown source. By the way, the French version of an epipen uses sulphites to conserve the product!

The juxt of it is that you need to get tested. 

Keep a food journal with not just what you eat but what you eat it with and where it came from (or what it came into contact with such as wine, is it canned or bottled or fresh etc) and with what meds.

Sometimes it is the contact between two different molecules that sets off the reaction.

Whatever it is it seems very sudden...you may wish to keep some benadryl by your bedside if it happens again...Take a little sip to stave off the worst of it.

I was told to stay on antihystamines for life because you cannot desensitize against sulphite allergies...once the reaction starts it is harder to get it under control so nip it in the bud early.

Sharon

Growing up, my daughter always seemed to have random hives on her body.  She was a soccer player and often took pain killer for her bumps and bruises.  Turns out, the hives were an allergic reaction to Advil.  We never could figure out what was going on until one day she took Alieve.  Her face blew up and looked like the Elephant Man.  We had to take her to the emergency room for fear of her throat becoming blocked.  If you look at the possible side effects for these meds, hives is always listed.  Turns out, she was allergic to the whole class of drugs - who knew.  

Another possibility could be your laundry detergent?  Have you changed it recently?

Good luck!

This sounds like a severe allergic reaction, perhaps to medication. I myself have had trouble with swelling of my eyelids and lips as well as hives, but it's kept under control by taking Reactin daily. I have thankfully not had difficulty breathing during these reactions.  My symptoms developed suddenly after a viral intestinal illness 2 summers ago. I woke up with a swollen lip and inner cheek, and later my eye swelled shut. After that first episode, I had further swelling of the lip and then began to develop hives in any area where clothing was rubbing (for example, pant waistline and around my ankle at the top of my boot/shoe). There were no specific triggers apart from the viral illness. I do have a severe allergy to gentomyacin (immediate swelling of the eyelids and itching) and a milder allergy to codeine (mild itching and rash). Otherwise I had never had seasonal allergies or other allergic reactions prior to this. I was not taking either med at the time I had the facial swelling. I went for extensive allergy testing which did not pinpoint anything specific as a trigger aside from dust mites, but I do follow up with an allergist every 6-12 months now. I was told this could be an autoimmune reaction, given the fact that I have UC.

I would suggest going for allergy testing ASAP, if you haven't initiated this already. The allergist did tell me that 75% of the time, the specific trigger may never be identified, but either way, you need to take precautions so that this does not happen again. Keep in mind that allergic reactions can strike out of the blue. The fact that you had some laboured breathing suggest a more severe reaction, and as is typical with allergies, each subsequent exposure results in a more severe reaction than the last.  You may need to have an Epipen to carry with you at all times. You should also always have an antihistamine such as benadryl on hand in case you feel a reaction coming on. But I am in agreement with Sharon: don't take this lightly. Go for testing ASAP. That is my advice.

Finally found the culprit. Got my blood-work back today and it looks like I've got the "Alpha Gal" allergy aka the "Meat Allergy". I scored a 60 kU/l whereas 3.5 is considered "high". It's the only known allergen to cause a delayed reaction several hours after ingestion. It looks like it's brought on by a tick bite but I also read that Crohn's Disease patients were more likely to produce the histamines too.