Doctor can examine
Bumps are hard to figure out without an exam. Sometimes, they appear and disappear for unknown reasons.
Bumps may be ok if there is no pain, oozing, bleeding, itching, etc... Otherwise, the causes may be irritant or allergic (something touched the area), or may be from blocked pores, blocked glands, irritated follicles, etc... A doctor can look at the bumps to help get a diagnosis.