What Is The Itchy Rash On My Legs After Having Oral Sex?

Hello,

I had oral sex with my boyfriend this morning and he ejaculated in my mouth for the first time. About an hour later, I got out of bed and went to the bathroom. I noticed that I had a bit of an itchy rash starting on the backs of my thighs and it spread to my chest and shoulders, neck and face while I was in the shower. All within about 10 min. Could that have been caused by swallowing? The other thing I was thinking was that I have a yeast infection and I took Monistat Ovule for the first time on Tuesday evening. Could this be a delayed allergic reaction to that? Thoughts?

Thanks