What Do Blood Oozing, Puss Filled Bumps On Arms And Calf Suggest?

I have been getting a pimple like sore, most are on my right arm but now have one on my left calf. When I say like a pimple, I mean: It festers up with puss but is a bigger head then a pimple and when squeezed it just bleeds a bit leaving a larger opening then a pimple that just scabs over red. The surounding skin stays pinkish. My leg sore was larger, sore to rub over and a bigger pinkish circle around the opening. Allergic reaction?