It seems like you might have a common condition called acne. Acne can appear as red pimples or a rash on your chest and head. It occurs when hair follicles become plugged with oil and dead skin cells. Hormones or bacteria may also play a role in its development. To make things better, try mild cleansers and don’t pick at or squeeze the pimples. If it’s bothering you, see a dermatologist who can give you advice tailored just for you.