Red spots on foreskin under glan

I'm 35 and recently (about a week ago) had red spots appear on the foreskin along the sides of my penis under the glan.  Three spots first appeared and then a fourth a few days later.  One spot on the left side has become less red, but the other 3 remain.  These spots do not hurt or itch, are only slightly raised, and do not have a head or blister. I don't feel any burning when I urinate, but sometimes I think I feel some faint irritation generally (but I think I'm focusing too much on my penis and imagining it).  It's been about 4 weeks since I last had unprotected sex with a woman that I see occasionally and who I know does not have STDs.  Before that I had sex with a woman (about 10 weeks ago), and while we were doing foreplay my penis briefly slipped inside her (for about 3-5 seconds).    I then pulled back out and put a condom on and immediately after sex I showered.  And I do not know her STD status.  I've never had these kinds of spots before, and I was last tested for STDs about 2 years ago, which came back negative.  I have an appt with my GP in about 3 weeks, but would appreciate some advice now.  I can upload a photo if that would help.  Thanks!