Alcohol....

In general, alcohol irritates the gut so you might not be able to tolerate it. But some people can. My cousin had Crohn's disease and was an alcoholic - but I wouldn't recommend that. He was also on remicade.

How long have you been on remicade and do you use meslamine enemas? At 18, I really didn't want to be using enemas, but it really helps. Also, have you tried a probiotic? I'm on VSL#3 DS. When I started that, I found that I had a bit more success with drinking (and everything else).

Also, what kind of alcoholic beverages are you having? I'm not sure where you live, but if you live in the US you'd still be underage and not drinking the highest quality alcohol. Two sips of Bankers or Burnetts and I'd be in pain. So nothing out of a plastic bottle for me. I also absolutely cannot drink beer. Just a few sips and my body feels completely weird. Wine is okay for me, but not great. And gin seems to be pretty good. But again, only somewhat decent alcohol.

I know there are a lot of people who would be thrilled to just give up alcohol if it meant they could be in remission, but unfortunately drinking (and eating) is a very social activity especially at your age. So it can be frustrating and isolating not being able to participate, and I totally get that.

Alcohol can be like a colonoscopy prep to some of us, while others have no issue at all. It varies. Listen to your body.

Beer often contains gluten, an allergen to some of us. You could try a gluten-free beer or hard cider and see if it's any different.

Wine contains sulfites an allergen to some. May cause issues if you have an allergy.

Some do better with vodka, rum, etc.

I won't preach what you should/shouldn't do.

I always had the best luck with vodka and soda. Anything with sugar added, beer, most wine, or anything fermented or too strong or in too much quantity would give me the craps in short order. I’ve given up all alcohol at this point, but I would suggest drinking only in small quantity and after or with food.

I used to have issues with alcohol as well but the speed of how long it takes to hit you has me perplexed so my information may not be all that helpful. For me, it would cause the bleeding and pain the next day. I am fine with drinking now although I don't drink beer, it's usually gin, rum, tequila, vodka, etc.
My issues with alcohol didn't die down until I dealt with the high stool volume and intermittent diarrhea. Slowing my bowel movements closer to a normal pace, reducing stool volume and using clove oil to increase intestinal mucus did the trick for me. I had solid theories going into this but they were based solely off my own symptoms. Even in remission, I plan to continue to research and restore normal bowel function as I see this as a likely contributing factor.
Side note, besides alcohol being alcohol, ethanol is a pretty efficient hydrogen donor which means certain biome circumstances will hate alcohol worse than others and be very damaging. I would reconsider alcohol at least until some normal functions are restored. Even then, the fact it hits you within 10 minutes has me doubting this is just large intestinal involvement. Do you eat before you drink?
Another side note, alcohol can cause diarrhea regardless of UC. Depending on the amount and proof, it can cause diarrhea in some cases and constipation in others so diarrhea after drinking is still likely a given.

Back when I flared I shared your symptoms from drinking alcohol. I'm currently in remission (no blood, no mucus, fully formed stools) and alcohol is perfectly fine although I don't drink it very often.