blood clots and cramping

Serenity
I have had an IUD for eight months now, for the most part things have been great but not lately. I will randomly get bad cramping as if I'm on my period even though it's not time for my period. Last night I got that pain really bad and realized I had passed a blood clot. Is this normal or do I need to go to the doctor?
I have never had these symptoms before and I am concerned that something is wrong. Please share your opinions on this I really need some advice!!