That sounds like a possible allergy to me. When I went off allegra (which I was taking every day for months), I got these little bumps on my forehead all over. As soon as I started back on the allergy pills, it went away.
My allergist didn't think there was any correlation, but I became acclemated to a new allergy pill, and there have been no more bumps.
Not 100% sure this is the cause but it seems logical to me.
Perhaps you should pay a visit to an allergist and see if you are allergic to anything. I have a dust allergy, so everywhere I go is dusty and I need to take a 24 hour pill daily.
Good luck...