I drink 7 glasses of water a day, sometimes a get a headache, but after i drink it does go away. could this be anything else?

Dehydration: If rehydrating helps it is probably dehydration which can indicate certain issues such as diabetes or low blood pressure.

Water intoxication: If you drink 7 glasses of water a day, it is unlikely that you have headaches due to dehydration. Rather drinking too much water can cause swelling of the brain cells (due to low salt) and headaches. Too much water washes out the kidneys which leads to an inability to concentrate fluid properly.