Muon, be ready to say good bye to your IBS. I have spent some 30 miserable years until recently, with terrible IBS symptoms. Pardon my language, farts like nobody, bloating, burps and belches like nobody, constipation was my nic name. Quantum initially put me to some tips, and then my solution has been a life-changer, one that I gathered from this forum, from somebody that cured his POIS, except that in my case while it eliminated my IBS but did nothing to POIS. I have to confess this POIS forum can be a magic library for all your weird ailments
1. Enzymes to digest food. Dirt cheap: Wonder Labs, Proteolytic Enzymes (this has Trypsin and Chromotrypsin - very imp). One tab after each meal. Somehow other expensive proteolytic enzymes didn't help me.
2. Feeding your friendly bacteria to slowly but positively change your gut microbiom. "Inulin" bulk powder. Cheaply available. I add it to my tea (twice a day, it tastes nice).
3. Bile Acids Factors from Jarrow after each meal. This would kill any remaining bloating IBS crap. If you ever wonder why vitamins you take do nothing, try this, it will help absorb all fat soluble vitamins. It will also help your thyroid by helping your Liver (60 % of thyroid hormones get built by liver).
Food with high fiber content tend to trigger IBS symptoms in me. For example whole grains. My stool will get messy.