L.M.
I have had four pregnancies and odd skin rashes at various times throughout have been a part of all of them. Mine often showed up on my legs after showering -how random?! That said, I'd wait for a positive home pregnancy test to know for sure. Your situation could be an allergic reaction to something he'd eaten before he nibbled you or something like that.
Best wishes!
PS. I highly recommend the ovulation prediction kits if you're in a hurry to conceive, they went three for three for me!