Hi Tracey
My k pouch (still a pouch just a different exit) is 35 yrs old and going strong.
There is no reason that a pouch should have an expiration date on it...it is still your own small bowel and is not made out of some man-made biodegradable material that falls apart after a certain time.
Sure your body is aging along with your pouch and so is your digestive system that was compromised to start with for some reason (whether it be UC, Crohns, fap or any other disease) or other so you may have problems linked to all of that but there is no timer on it.
My valve (k pouchers have anti-reflux valves to allow things to stay in and come out when needed) is the fragile part of my pouch because it is delicate and constantly being used but my pouch is just a piece of gut that was refashioned for a slightly different use.
There are foods that I used to eat that are on my no-no list now like most breads, cakes and pastries, pasta and potatoes but I can still manage rice occasionally and full grain black bread or some other rough whole grains.
I have wittled down my diet to things that work and end up with mostly proteins with an overcooked green veggie or salad and some fruit afterwards...my pouch likes that...if I go off the ranch then I know I am in for some serious trouble...diary means gas, pain, cramps and bubbly output for days...starches mean wall-paper paste...fibers mean hell in a handbasket for a week...It is like knowing which cards to play in a game...if I throw out the wrong one, I pay.
I would honestly do a 3-5 day liquid fast (this is a personal thing) to sort of reset your system (I tend to do them about 2xs/yr) where I mostly drink teas, juices and broths and then gently re-integrate 1 protein at a time like chicken breast in broth then another etc the next day...it takes me about 10 days to get my body back to eating 'normally'. By then I am feeling better and my pouch is more cooperative. Please understand that just because it works for me doesn't mean it will for others but it is a simple elimination diet that my doctors have used on me for years.
I take advantage of stomach flu or a cold to do it...once I am not eating anyway I just keep going...
By the way, I don't eat fast foods, eat mostly organic so I have little or no chemicals in my diet so that may be part of it...not sure.
Good luck and I hope that you manage to get your pouch back under control.
Sharon