Hello,
This pimple on the penis can be folliculitis, cyst , molluscum contagiosum(multiple, small, dome-shaped papules, often with a central depression or plug) or genital warts(caused by HPV infection).
Apply warm compresses, Neosporin ointment and calamine lotion and avoid messing with it. You can take anti-inflammatory pain killers like ibuprofen or acetaminophen. If the lumps persist then it will be best to get it evaluated from a dermatologist.
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.
As a general rule (and I've been told about this by sooo many dermatologists), you should NEVER pop/pinch/squeeze your pimples! Let alone when you have them on your penis! The penis skin is considerably thinner than the rest of the body skin, making it prone to various sanitary problems. If they keep coming back, they might not be pimples after all, they might be something else. Leave them alone and see a dermatologist right away.