Sex help..?

Hi ladies! I’m still fairly new to sex and all so I have some questions/concerns. Ever since getting my IUD back in December 2018 I’ve been sexually active. However, every time after sex and I cramp the day after and sometimes and bleed and/or spot. Almost like a period. It doesn’t matter if we go slow and easy or not. It never hurts during sex and I never bleed during sex. It only starts the day after.

Is this because of my IUD? Or something else? I have a gynecologist appointment in August but I’m just wondering. I haven’t been pregnant or had any scares either. I could use some insight!