I think my you should see your GI. You might have cuffitis, pouchitis or some other problem.  Because you feel different it may be due to there being a problem that may need medication.  It's sad that you have to give up playing the game you love because of your j-pouch.  Hopefully things can improve. 

I'm with Marie. When a J-pouch is healthy it doesn't stop you from enjoying whatever life has to offer. It's best to find out what's wrong and deal with it, if possible. 

Right now I'm not sure about my GI. The one I trust and I regulary went to moved to another hospital which is about 4h away. So that's not a very good option right now :/

In my hometown I haven't found anyone yet who I like being treated by

I'm quite sure I don't have pouchitis. I've had it before and symptoms were quite different.

I'm not sure about cuffitis, that might be worth considering. I'm about to start a treatment against it. If I'm informed correctly you do so by giving mesalazine, no? Typical UC treatments often are cortisone (prednisolone or budesonide). May I try them first? IIRC mesalazine didn't show that much improvement when I was treated for UC.

It's best to get a proper diagnosis before treatment, although in some cases treatment can be the best way to confirm a diagnosis. I wouldn't usually put cuffitis in that category. 

The fact that mesalamine failed to control your UC isn't good news, but it's also not a guarantee of failure for cuffitis. You can essentially bathe the rectal cuff in mesalamine, which you were never able to do to your colon. The side effects of mesalamine tend to be much less troublesome than steroids, which is why it's usually tried first. 

There is several other treatments. My Internist looked up the textbook treatment and prescribed for me once.  Anucort, hydrocortizone is a good inexpensive suppository and Canessa is the expensive Mesalamine one.  There are also enemas. I could never get it fully under control even using both types of suppositories daily. I am not the normal case as my j-pouch ended up failing.

Anal pain was often my first and primary symptom of pouchitis, later followed by night time incontinence (but I have a bad sphincter, so with a good sphincter the anal pain alone could have persisted for much longer before nighttime incontinence would have set in). Lots and lots of treatment options, but agree you need to get a proper diagnosis first.

Dont let treatable symptoms get in the way of living the life you want to live!