"Settling down" means that if you get bleeding, pain, acne, greasy hair after having the coil fitted, then after a few months (up to 6), it should ease or even stop altogether.
I suggest you keep a daily diary of your symptoms, this will give you some ammo if you need to do battle with your doctor.
As suggested on you new members thread. If you are not at all happy with the mirena coil then go & get it taken out. you should not be thinking that this is a punishment - it is your choice, so use it.