ok I'm a 21 year old college student and i don't know if anyone else knows about this but it happens occasionally to me, I'll be doing something that gets my blood pumping in general, and suddenly I'll get a short but very sharp pain in the right back of my head, as soon as i calm down it disappears, it usually shows up about the same time my sinuses act up but most of the sinus symptoms have gone away, and the pains remain if i get exerted. anyone know what this is, I'm getting worried