It's true that drinking water often relieves headache pain, because when you are dehydrated you tend to have headaches (and you dehydrate easily when you drink alcohol)

Maybe you are starting to suffer from migraines, and it's highly unlikely that it's due to a blood clot or a brain tumor,...
Actually often the pain is produced by the muscles around your skull. The brain itself is insensitive to pain, one could slice it without you feeling anything (when you knock your head, pain comes again from the skin and muscles around your skull).

You should probably go to see a doctor. If you don't have money ask your mother. I would be very surprised if there really is no way for you to see a doctor (do you have a medical insurance, social security). If you don't have access to medical treatment, that's what I would worry the most about, and would adress that issue right away.