Hi, 2 Or 3 Times I've Had What Looks Like

Hi, 2 or 3 times I've had what looks like very small blisters come up on my Penis. Painless and majority of the time itch less. Been swabbed twice with no bad Ness to follow. Doctors seem to think I'm all of a sudden allergic to highly fumagted things like lynx shower gel. At 24 I'm not convinced and always used it. I apply a dry skin condition cream and they dissappear after a couple days but end up returning a few months down the line... any ideas?