The last two times I had sex with my girlfriend I've bled after, often a substantial amount (what would basically be equivalent to a pretty light menstrual flow). I didn't feel any pain or anything out of the ordinary while we were having sex - I only knew I was bleeding because she pointed it out to me. She doesn't have super long fingernails but they could possibly be a bit sharp.
This is pretty much the only time I've bled after sex so I'm worried that it has something to do with the IUD (even if being accidentally scratched by my gf is more likely). Thoughts?