how to drink for a Sensitive stomach

I used to be able to handle drinking a lot more in uni, like 7-8 shots , no nausea or puking, just very drunk even if I was on an empty stomach. Fast forward 5yrs and I drink less now so I don’t think I would go past 3-5 shots. But weirdly the last few times I drank, I was either very nauseous or puking. Yesterday I had some wine before dinner (oysters and seafood) and didn’t even feel drunk but my stomach was not feeling good. The time before I just had 1 or 2 Muay Thai’s (12%) and I was puking ALL NIGHT and in the morning. Idk what happened to me and I’m going to Mexico in the next few weeks for my friends bachelorette. Obviously I want to have fun, not puke, and not be that friend anyone needs to watch. What should I do to make sure I don’t get nauseous or puke when I drink? Should I refrain from any particular alcohol or combination with something?