I've noticed I've gotten four pimple like bumps on my left breast. Do you think this is just acne? No pain, itching, slightly inflamed like a pimple

Could be pimple but. It may be pimples but we can not say for sure without looking at it So get it checked from your doctor if it persists or spread.Dont sqeeze the pimples.
Maybe. This could be acne, hard to tell without seeing it, or it could be a mild folliculitis, an infection of the hair follicles. If it is warm where you are and you are sweating, it could be some heat rash. See your doc or try a virtual consult here on health tap to evaluate and confirm.