I'm 28 years old, usually not a heavy drinker but was on vacation and pushed the limits -- drank 10-12 drinks a night every single night for 2 weeks (that's right 14 days in a row). Got very little sleep and honestly didn't feel too bad.
However now after a few days of rest I had a single drink and immediately got a throbbing headache, felt very drunk (not in a good way) and felt a lot more disoriented and lethargic (instead of energized) while. Felt very tired and had a throbbing/piercing headache in specific parts of my head the next day. Not sure what is going on as I don't think my alchohol tolerance should suddenly go down.