Did he test the "pimples" for HSV (the herpes virus). Seems that would be a prime suspect given the location and timing of the pimples.
Hello,
Without examination, confirmation of a diagnosis is tough but it can be contact dermatitis, rash due to friction rub, folliculitis, cysts ,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
Hope it helps. Take care and please do keep me posted on how you are doing. Kind regards.