I have severe pain at the base of my skull that radiates up behind my right eye. could it be a pinched nerve? is there a good way to tell?

Occipital/Trigeminal: Could be your occipital nerve irritated or your trigeminal nerve. I would have a trained pain specialist that evaluates for this kind of pain to help with diagnosing it and treating you.

CervicogenicHeadache: The most common cause of a cervicogenic headache is a stress to your neck and spine due to a bad posture, previous trauma, bulging disk or pinching nerve. The treatment is conservative, nonsurgical and reversible. Re. See a headache or orofacial pain specialist.