I feel sick. Why? (20 characters)?!

So it started jan 1st where I was feeling great the day before but when I woke up I wa practically crying because my head hurt then I threw up 4 times and fell back to sleep for a long time.My head still hurt for a few days after -we were driving most of the time- but then I felt fine.We thought it was just dehydration so the next time my head hurt I dosed up and water and have been drinking more but maybe I didn't the last few days because my head hurts again. Someone diagnose me please. This is not fun