hey so i have a lot of personal experience with stomach problems.
Two things have helped me. You are probably aware of these solutions but in case not
1) probiotic. I used to take a vegan yogurt but i suspect the amount of probiotic was tiny (they never listed the amount which is suspicious). So I started taking a vegan probiotic supplement called Tumbiotix which has helped. Can get for 7-10 pounds for a months supply online I think. OneClickPharmacy seems cheapest as for lot of things.
2) Peppermint Tea. You can get peppermint tablets too which are stronger but tea is fine for me.
3) Eating something plain like rice cakes, spread and hummus when the stomach gets bad and needs calming down. I usually combine this with peppermint tea.
JS - They think it will open the door to folk like LordMuppet campaigning for a threeway?