Hello,
It can be due to a small sebaceous cyst. A sebaceous cyst is a closed sac occurring just under the skin which 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.
Generally no treatment is required but they become painful then it means they are infected, then surgical excision by traditional wide excision, minimal excision, and punch biopsy excision may be required.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.
Not sure about the red/black bump, but squeezing can actually make it worse and can even cause a permenant blood blister. I'd have it checked out by a dermatologist. As for the acne, I have PCOS and am constantly dealing with it. I recently started using neutregenia skin id and LOVE it. Consumer reviews show that 80% of women have had positive results from it. It isn't that expensive to try either.