Sudden Inability to Drink Alcohol

I can’t drink alcohol anymore for some reason.

I used to (almost) have a drinking problem about a year and a half ago where I would drink most nights and sometimes days. I was just going through stuff but I’m good now. For reference, on nights I used to drink, I would usually have at least six drinks. When I wanted to change this behaviour before it became a habit, and I just quit drinking (with the occasional night that I would get drunk again, but never alone anymore; just at parties with friends). I’ve only drank about a dozen times since that period of my life and I’ve developed other healthy ways of dealing with my problems and I don’t need alcohol anymore, BUT I am in college right now and want to party with my friends the occasional weekend. A couple of days ago we were getting ready to go out to a club, so we were getting ready and pre-ing with our alcohol. I had one mixed drink, my stomach hurt a bit, then I had one more shot and immediately threw up. I played it off and waited until we got to the club to try having some drinks again. I had maybe 4 mixed drinks and didn’t feel any of the effects of the alcohol. All that happened was my stomach hurt a lot (the same feeling as when you over-eat and become bloated). This same thing happened the last time I drank too (about two months ago). I am still very young obviously, so I don’t understand why my body is unable to handle alcohol anymore. I’d like to hear some possible explanations as all I’ve found on google are instances of “alcohol intolerance” which seem to typically happen later in life.