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.
I hope it helps. Take care and regards.