Why can’t I drink?

For some reason, my body recently started repelling alcohol. Whenever I drink there are two outcomes: I drink too little and don’t get very drunk or I drink too much, throw up and don’t get drunk at all. Both leave me frustrated. My experience with alcohol is not very big. I’ll explain how my previous drinking sessions went to make my situation easier to understand. My first drink was vodka two years ago, I had 3 shots, got mildly drunk with no problems. Three months ago at my friend’s birthday I was drinking vodka again. I drank way too much, one bottle + some more (the bottle was probably 0.25 litres), about 10 shots. I didn’t feel sick at all while drinking. Even while throwing up down the toilet it wasn’t that bad, I was feeling pretty good as far as I remember. But 5 days ago I was celebrating school graduation with my class, I got my hands on vodka yet again. 2 shots in and I threw up. I was really weirded out but I decided that I probably didn’t eat enough. Filled my stomach with some meat and salad and continued drinking. 4-5 half shots in, all of it came out again. Dammit! A friend told me it’s probably tomato juice I’m drinking after shots. I started drinking apple juice instead. It didn’t help. I threw up a third time. Half a bottle (the bottle was 0.5 litres) was finished but I was not drunk at all. My friend tried my vodka and said it’s quality is really bad. I gave my bottle away to another friend and he later told me (2 days after the celebration) that he still feels sick from that vodka.Thankfully my friends got me some wine and the rest of the celebration was very pleasant for me. Right now, I have good vodka with me (I asked various people), I had 2 shots and I feel that if I’ll drink more I’ll throw up. Can someone tell me why? Alcohol flowed so easily at my friend’s birthday. Why is it different now? Could it be tomato juice? Could it be bad vodka I had 5 days ago? Could it be something else?