Got my IUD 3 weeks ago IS BLEEDING NORMAL

Before I got the IUD i had my son 5 months ago. I've been having so many problems after having him with cyst endometriosis pain etc. my OB thought this would be a good idea for my pain. Before it was placed in I was having two periods in one month and I am having heavy bleeding I've gone to the ER once because I've been having low blood pressure bleeding from the back... throwing up etc I've been passing huge clots the pain was so bad I cried that's the reason for the ER visit the IUD was placed correctly... the bleeding though is worrying me even before I got the IUD