30 years ago i had experimental brain surgery to remove a blood clot and skull fused together with no plate- no constant headaches, could this be a cause?

Probably no: There are several causes of headaches. It is unlikely that they haedaches you are currently experiencing is as a result of the surgery you had to remove a blood clot 30 years ago. I will recommend that you see a neurologist, who will perform a detailed neurological examination and probably order several tests and imaging studies of the brain, to help better understand the cause of your headaches.

Probably not: Although constant headaches have been reported after craniotomy surgery ("post craniotomy headaches), due to the time period involved i would think that the headaches are due to some other cause. Consult a neurologist or your pcp.