I have had a extreme headache for 9 days, the doctor tried migraine pills which didn't work,now he has me on vicodine which doesn't help completely, he did a ct scan to check my brain out, and said I have something sinusitus, which they said is basically a beginning of a sinus infection but it is in the back of my head. please explain this to me. how is it in the back of my head I did not know there is sinuses in the back of the head. He put me on 850 mg of augmentin