Semen on Skin = Rash

I'm a male 22, don't smoke, rarely drink.
I ejaculated on my girlfriends shoulder, and almost immediately after there were small red dots only where the semen had touched on her skin.
It went away after about 30 minutes, but this really freaked me out.

I have had some uncomfortable pressure in my prostate area in the
past and weird kinda feeling inside my penis a couple months ago.

Could this be bacteria, parasite, or something in my semen that is causing a reaction to her skin, and what doctor would I see to check?
She said it didn't itch much or anything and the skin didn't raise, it was just really red with a bunch of dots.
Odd I know, luckily we haven't had sex yet, and won't until we figure this out so any insight into it would be much appreciated.

[Bhupinder Kaur, MD]

Hello,
Semen consists of sperms, proteins, proteolytic and other enzymes as well as fructose. Normally it does not cause any allergic reaction or contact dermatitis but in your case, it looks like your girlfriend is having semen allergy. It is due to proteins in semen or other allergic substances transmitted in semen like some medicines.
You can wear condoms the next time you have intercourse and if the symptoms persist even when there is no contact of semen with her body then other conditions need to be ruled out. But if the symptoms decrease then semen allergy is the likely diagnosis.
I hope it helps. Take care and please do keep me posted on how you are doing or if you have any additional doubts. Kind regards.