Why do I throw up the next day after drinking?  

Alcohol... Usually when we overdo it; we forget to eat. The lack of food, and the aggravating effect of alcohol on our tummies, usually causes an increase in stomach acid which if not absorbed...Well; you know the rest.
Many things. Your body is giving you a message! alcohol inflames the esophagus and stomach, increases chances of reflux disease, and can worsen peptic ulcer disease. It also inflames the pancreas. Any of these things can be causing your vomiting. You need to listen to your body and stop alcohol, especially if drinking 2 or more drinks. See your doctor for a GI evaluation and meds if needed, and get help.
Alcohol can be toxic. There are reasons why alcohol withdrawal or other after-effects of drinking alcohol including irritation of you stomach's lining may result in one "throwing up" after a binge. Questions like this may reflect an unhealthy relationship with alcohol. Most healthy people would simply not drink alcohol or as much based on these effects on them. This is particularly true at your age. Ask for help?