Mirena coil concerns

Elisha
Hey guys, just wanted a little bit of advice on something! I've had the mirena coil for 5 months now without any kind of period (which has been great). However this morning when I used the loo, I noticed a bit of brown discharge on the toilet paper. I went for a long walk in the day and coming home I felt that little dribble feeling so went to inspect and noticed that I've had more discharge. Can anyone tell me if this is normal? Obviously I know the coil can cause spotting and stuff, but seeing as I've had it in for a while and without any period, I'm concerned as to why I'm getting this discharge. Is anyone able to shine some light on this for me?