My son is 15 months old, typical daycare baby medical history (colds, stomach viruses, ear infections). When I was bathing him today, I noticed a small, round bump about 1/4 inch below the head of his penis. I use a&d ointment in his diaper area daily, and Desitin if there are ever signs of irritation (not the case at this time). It does not appear to be painful to him, as I did push on it to see if he reacted -- which he did not. What could this be?