Does Friction From Intercourse Cause A Rash?

Hi I went to the doctor and they treated me for bv and yeast infection but I also had these tiny bumps that itch like crazy on my buttcheeks but more so towards my vagina and I did itch it a lot and when I took showers I use to itch it as well. So I m done taking my meds still had the bumps my doctor said they were ingrown hairs and I put Nair on it when I was shaving because I didn t think it would bother but as I was wiping the Nair off and got out the shower its reaaaaallllyyyy red down there and looks like a diaper rash any home remedies? Also can friction from intercourse cause a rash?