newcomer IUD

I've had my Merina Coil put in on the 14th December. I was told by my doctor that i couldn't have unprotected sex with my boyfriend for the first week. Last night we had sex for the first time without a condom but I've been spotting very lightly for the last 3 days, and cramping. after sex I have found my flow to be no more heavy on a pad. But every time I use the toilet the paper has a coating of blood(sorry for tmi; because I am used to having extremely heavy periods and quite large clots I have become accustomed to look). Just looking for some advice. Will I be safe? I'm not going to find that I'm pregnant am I?