Sounds like it's directly linked to hormones. Do get a pregnancy test. Some women have babies even with the IUD. Or if it's the Miranda (?) it could become imbedded in your ovary and be causing some hormonal problems. You might want to have that thing removed and try a different kind of birth control since so many are suing the IUD manufacturers for so many kinds of problems it causes. - I had an IUD back in the day, when they were new - and ended up with a PID and had a hysterectomy. Not saying that will happen to you, but do see a doctor.
you still could be pregnant and have period type bleeding. maybe its because your period is about to start or ovulation.
Rub Keo Karpine oil. It may help. I was having red rashes on body. I used it and worked.
do u drink alot of caffine? i know to much caffine intake will cause breast pain,cause it's happend to me plenty of times!