Sex and now itching

My ex and I broke up for a little bit. We were having sex during the break up but then we stopped. Now we’re talking about getting back together and of course having sex. I knew he had sex with two other girls but he said he wore a condom. We have been having sex ALOT. I shaved and got a little bit of razor burn and after that I have been really itchy and kind of swollen (I’m assuming is from us having so much sex) but why am I itching so much?! That’s literally the only symptom I’m having. I think maybe a yeast infection? But it’s only itching. I do plan on getting an std test since he did sleep with someone new. But in the mean time; tell me if this is normal.

DON’T come at me for having sex with him. We have kids together and I didn’t want a new body.