why am i rejecting alcohol

i dont understand like i was frinking WAY more last weekend but inwas chugging a double shot of whiskey and i IMMEDIATELY vomitted it back up and i ate before n all that shit like why is it not working? i had like 8 shots last weekend and i threw up but not for hours after i drank and its bc i dtank too much this time it was like barely anything but my stomach literally wont tolerate it and i dont think its the TYPE of alcohol bc when i was unwell i drank like 4 shots of iack per noght EVERY NOGHT and i was fine?? im so confused