Always feel sick.

So like I don’t drink a lot the most you can get from me is 4 cans (depending on what) and I’ll be done. So I would say I only drink on special occasions like birthday and hangouts with my mom so its not often. Few months ago I was drinking with my bf and mom and I honestly had to much I blacked out, but since that time I wasn’t able to hold any alcohol in and being near it without feeling so nauseous. I really don’t understand why this is happening. I have asked around but never really gotten a full answer.