When i scratch, bumps suddenly appear. Why could this be?

I have several bumps around my body now. A couple on my legs and feet, one on the edge of my nose, a small one on my eyelid, another underneath my eye, and one on my temple. These are not pimples, i can assure you. I haven't done anything different either, no new creams or lotions, or anything like that. Is it the heat?