Are you maybe getting sensitivity to a food. I know a few foods I stay away from due to them causing me gas. I don't fart unless I'm on the toilet, so I know a lot of gas/belching can be painful to deal with. Trying the low fodmap diet may help to determine if it's food related. The only other thing I can think of is pouchitis causing excessive gas.
Sorry I can't comment on the other things you mentioned as I have no reference. Good luck