I had iui 10 days ago, and this morning i had brown discharge, pain on my back and breast, is this normal?

YEs: Either it is the start of implantation or the beginning of a period. You will know over the next 3-4 days. But it is very normal.

IUI: What kind of IUI did you have? Have you been treated for it? Are you still being treated? Did you have an ultrasound of your pelvis done? Were any cysts found if you had one done. Brown discharge doesn't tell me what the cause of it is. Pain in the back and breast may be related but are not specific.

Likely yes: It could be that your period is getting ready to start. It could also be implantation bleeding from a very early pregnancy. If it is implantation bleeding the bleeding will be light and it won't become like a normal period. Only time will tell which it is.