What Causes Bleeding After Intercourse While On IUD?

Good morning?! I am a 5'10", 29 y.o., mother. At my 6 week postpardom check up, after i had my youngest child, i got an iud. That was a year ago. First of all i still havent lost all the weight from that pregniecy like i did with the 1st two. I weigh 175 now insted of my usual 145. I just thought I'm older and its normal. But about 6 months ago i started spotting after sex and every time he hits my uteris it hurts, like the worst cramps ever, the spotting gradualy went away but the pain has gotten worse. What do think is wrong? I want it taken out! Will it be easy to remove? And will my simptoms go awat?