I had similar problem for some time.
I lived in cambodia for a year, and theres little there in the way of dairy, so the day I got back to thailand I gulped down a big bottle of drinking yoghurt and had to run for the toilet (a few times). But after that, every time I tried to move I felt wiped out, and was bloated. I could do very little at first. This gradually improved, over a year or so.
When I got back to uk, it got worse, with the wine and beer. My guts were bad
I had some blood tests, nothing was found
Anyway I cut out the alcohol,and SUGAR, and coffee,
I try to eat a lot more protein, less carbs, and its much better now, it doesnt get worse when I exercise
I still have a lot of dairy (I’m semi vegetarian)
I’ve also been on Omeprazole for a few years now