First IUD, Mirena!

Alright, a little background info, I am 17, started having sex at 15, got on birthcontrol, and boy it was fantastic! I switched pharmacies because Walgreens/ CVS was no longer covered by my insurance. When I switched pharmacies, they switched my birth control to a different brand. This brand messed up the balance of my hormones and cause extreme anxiety and depression. Switched again and caused extreme break outs. Also taking a pill in my busy life, too hard! So I got the little T! The experience was most definitely different and the insertion it's self wasn't painful, however after felt like period cramps from hell. I am now on day 3 and I am having brown kind of thick discharge, is this normal? Should I go back in to get it checked? No longer in pain, just curious. Thank you in advance for the advise and information 😊