What Causes Headache Over The Right Eye And Behind The Head?

I have had a headache over my right eye and sometimes the back of my head on the right side for months now maybe longer. I had a tooth filled a couple of weeks ago, and there is a tooth beside it that has a cavity. It is a little sensitive when I eat something sweet. I ve been flossing twice a day to keep out any food particles and gargleing with hydrogen peroxide and water to hopefully keep it from getting worse til my next dentist appointment. They didn t seem too concerned when I told them I had been having headaches and wondered if I had an infection. I am really getting tired of having these headaches. Could this be the problem?