Anyone else had this?

So, I like a drink or two! I started drinking later than most people, but used to enjoy going on nights out and sometimes getting drunk. However when I drink now, I’ll get a bit tipsy after one or two, then I’ll just start feeling sick, headachey and really thirsty and can’t seem to get the same buzz from alcohol that I used to. Any ideas as to why? It’s ruining nights out and social occasions for me, especially since I do like alcohol.