Suggest Remedy For Unbearable Headache

Hello Doctor,I'm 31, 5'10 and 178lbs. I had a brain surgery last year for my epilepsy. 2 months after that (June 2010) I developed severe depression for which I'm still on medication. I also take my anti-epileptic drugs. Now I have another problem. When i put my head backwards i get this unbearable headache. It's like my head has been tied to a rope is being swung. I can't even maintain my balance I get "THROWN" atleast 3-4 feet if i don't hold on to something(or someone holds me). I just can't put my head backwards, If i'm sitting I can't lay my head, I have to sit straight and worse is that I can't sleep straight I have to sleep sideways (which I discovered after several bouts). I have this since past six months and my neurologist can't explain it. Please advise.