Semen Allergy?

So the bf and I had sex last night and he came inside me. This morning I woke up and was burning everywhere the cum had been. Like all around the lips and leg joint (he came a lot. It’s been like 2 weeks since we last had sex). I googled if it were possible to develop an allergy to semen and it’s totally possible albeit uncommon. Now I know it’s not an std bc I know with 100% certainty he’s not cheating plus I’m reasonably certain that an std would take longer. Have any of y’all ever had this happen? Cause semen allergy is gonna be 1 of 3 options. #2 would be Beard rash and #3 would just be that it leaked too much and the moisture caused a rash of some sort (I’m a + size woman so I’ve had similar before from running around in the heat, sweating and then having it get rashy down there.) So. Anyone had anything similar?