I have a weird reflex after the first sip

I’m wondering if anyone also has it or has an explanation for it.

I have been drinking since I was a teenager (15 – 16). Overall, I know how to handle myself and would even consider myself a heavyweight drinker; nowadays I do not drink that often, only around once or twice a month, but I still maintain a very high tolerance, but ever since I was around 21 (Post-Covid) I went for a long while without drinking, and after my first sip of an alcoholic drink (rum) after a long time, I felt like vomiting.

I was extremely confused since I’d only vomited twice while drinking and those were only after drinking stupid amounts of different alcohols, only twice after dozens and dozens of times, but never right after the first sip. I managed to hold it in, it was like my body was reacting negatively to the alcohol; funnily enough, after that I tried a second, third, and nothing, for the rest of the night I drank like 4 other glasses of rum and it was completely fine for me.

After that it has been the same everytime, one sip of a strong alcohol or a strong beer, and my body has this reflex, like it’s trying to push whatever I drank out. Weird enough, one day I was offered this liquid supplement by a co-worker which smells just like rum, and my body reacted the same. I am completely fine after the first drink and can pull an all nighter like always and drink pretty heavily, but it’s pretty annoying and I wonder if I have to deal with it the rest of my life.

Does anyone know why does it exactly happen or how can I beat it?