it hurts!!

I love having sex with my partner. we have sex 3-4 times a week, were both SO attracted to each other. We’re freaks & do everything right, but every now and again it will hurt, it will sting so bad. After a few couple strokes it goes away, but before then it hurts me so bad, it makes it uncomfortable for my down stair area & then during sex i won’t stay wet even though it feels SO good i can just tell it’s rubbing me raw. I’m on the nexplanon birth control implant, could that be a factor? is it an infection or maybe even because the fan blows on us... 😂😂 please help me out. i hate the DR!!