IUD and Sex

I’ve had my copper IUD for about 13 months. And in the past 6-8 months I started spotting every single time I had sex. But I think this started after having sex with a large parter. My partner before him I never bled after or during sex, since this large partner every time i have sex I spot. It doesn’t matter the size or intensity of the sex, its just every time. Has anyone experienced this? And how can I go about preventing/treating this. It’s very embarrassing!