Spreading Pubic Rash

A little over a month ago I had sexual intercourse and immediately after I noticed a rash in my pubic area.  Since it was right after the incident and since I had shaved that area the night before I thought it was a simple issue of in-grown hairs.  However, since then the rash has spread exponentially to areas outside the pubic hair region and onto my inner thighs.  the bumps which are on the public bone are small and pimple-like while the bumps in the inner-thigh area are larger and poison-ivy bumps with no pimple-like qualities.  I have researched a bit and thought possibly pubic lice or foliculitous.  I've had foliculitous before on my leg this summer from a bad rash and I have been doing hot yoga lately if that helps anyone to diagnose me.  Plus it is unbearably itchy at times and seems to be concentrated in my inner-thigh area. Thanks for your help.