It's difficult to tell you exactly what this is without examining you, but if what you have are marble size or larger moveable knots in the deeper subcutaneous tissue, I favor pilar cysts.
The only treatment for these is surgical excision. On the other hand, if it's small pimples
in the hair follicles I favor a rash
like condition such as acne
necrotica or lichen planopilaris. See a Dermatlogist!