Burning after he ejaculates

I am recently married and we have recently stopped using BC. I have notice after he ejaculates I get a burning feeling in my vagina. It only lasts for about 15 minutes, but still not pleasant 😐. I have no signs of infection, (discharge, itchiness) and the sex itself does not hurt. It burns only after we have sex. I thought maybe we were not using enough lube and have increased that but it has not helped. I have heard you can be allergic to semen but that is supposed to be rare. Any help or similar experiences?