Tips for getting drunk without getting sick or getting a headache?

So when I was 18-19 I could get drunk really easily without any issues. I am and was still a lightweight but I could actually drink and have a good time. I still threw up from time to time, but could happily and easily get drunk after three drinks 99% of the time without issues or throwing up.

Now at 22 I struggle a lot. I hate the taste of alcohol, I did before but now it’s like one I start drinking alcohol I have a gagging feeling and often throw up from the taste and how it makes me feel gassy in my throat. Either that or I get an immediate headache which I didn’t before. I’ve tried drinking water whilst drinking alcohol, eating a lot and I still get the same problems. Why can’t I drink like I use to and how do I drink without these problems ? Any tips?