The symptoms that you have described are typically suggestive of a sebaceous cyst. It occurs just under the skin and contains a "pasty" or "cheesy" looking substance called keratin. They may occur anywhere on body but scalp, ears, back, face, and upper arm, are common sites for sebaceous cysts. Blocked sebaceous glands, swollen hair follicles and excessive testosterone production will cause such cysts.
Generally no treatment is required but if they are unsightly or if they become painful then it means they are infected, Then surgical excision is required which is done by a dermatologist. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.