What Causes Brown Discharge And Dizziness After Fitted With Mirena Coil?

I had the mirena coil fitted 6 days ago and because i am going away for a week the doctor gave me norethisterone to stop any bleeding while away. I bled for the first two days after having it fitted but since then have been getting i browny coloured discharge everyday and yesterday had a few pains in my abdomen and then went light headed and felt sick. Could you please tell me if the discharge is normal and if the dizzyness could have something to do with the coil? thank you