A headache can be a sign of dehydration. You have to drink. Try sugarfree popcicles. During the day while you are feeling good, try to get more fluids in so that you won't have a lag latter.
I agree it's probably not getting in enough fluids but I also know that when I was not getting in pretty much anything if I had some chicken broth my headache would go away because of the sodium. Hope you feel better.
Didi ..... Sleeved and living my NEW LIFE!!!!
Highest WT 381 Surgery WT (367.8) Current WT 236