I’ve also suffered with IBS for many many years and have trouble with a distended belly but have never tied it to (after a bowel movement). I will start watching. My issues are or seen to be tied to eating foods that do not agree with me…especially dairy. Dairy hates my guts. And I love ice cream. About once a month I will eat some ice cream and pay the price but other than that I do not keep any sweets or ice cream in my house because I’m weak in this area. Don’t know if this helps you very much. I also take probiotics the live ones kept in the fridge but not all the time only when I get a belly ache and it calms my gut immediately. Good luck.
Try taking a lactate pill with your ice cream or buy lactaid ice cream! It really helps!