What Causes Reoccurring Bad Headaches With Slight Nystagmus?

I have been getting reoccurring bad headaches that begin behind my right eye with excruciating pain and traveling down to the back of my neck. it seems to happen only when I'm immobile our concentrating on something ie tv or computer. I have slight nystagmus that only happens when I move my eyes to the corner of my sockets. The only glasses I need is the weakest prescription of the reading glasses otc. And I only need to wear those when reading. Please give some insight. I'm a full time college student and part time youth pastor with no m.i. So I can only go to a dr as a last resort. Thank you