What Causes Abdomen Cramps While On Mirena Coil?

I had a mirena coil fitted 17 months ago, had the usual problems spotting stomach cramps etc. for the last 12 months its been fine but recently I have noticed a smell down below, I had an itch and treated myself for thrush, it went away and now its back, no itch just a horrible pseudamomus type smell. I use a vaginal gel for BV and it seems to work, any idea what else can be causing it?