Switched from liquor to beer, now my stomach is wrecked — why?

25M, 185 lbs, 5’11”. I used to drink a fifth of tequila a day (IBS issues), but recently switched to drinking 18–20 Coors Banquet beers daily. Ever since, my stomach has been destroyed. Anything I eat goes right through me — immediate, painful bathroom trips, burning, cramping, even fear of using the toilet.

When I do go #2 it literally itches and burns soooo bad afterwards Literally wouldn’t wish this on anyone.

I don’t understand how beer could be worse than hard liquor. The volume? The carbs? The carbonation? I’m planning to see a doctor about my drinking, but this reaction to beer specifically is confusing and miserable. I enjoy coors alot my favorite beer but I’m not sure why it’s hurting me

Anyone else go through this? What the hell is happening to my body?