It occasionally happens that women experience discharge with a strange odour. This has nothing to do with the copper coil itself. Usually, the smelly discharge is caused by a fungal infection, such as candida. A candida infection is annoying but relatively harmless. We recommend seeing your GP in this case. The doctor can prescribe you tablets or a cream to fight the fungus.
It is very important that despite that nasty smell and discharge, you do NOT wash your vagina with soap or foam. So wash only with water. Do not use vaginal rinses either, as they only worsen the situation as it disrupts your vagina's natural balance.