Hi, I'm 17 Years Old.. I Was Sexually Active 5

Hi, i'm 17 years old.. I was sexually active 5 days ago. I'm on the IUD and have not had a period since i got the iud inserted. The day after i had sex, my lower left side had a constant pain.. and the past couple of days i've had cramps (not too bad) but today, they have gotten worse and when i went to the restroom there was brown spotting. My boobs were aching yesterday but it's not too bad today.