Hi, coils some times cause heavy and irregular bleeding especially during the first 3-6 months. It may also cause painful periods. All this usually represent body's reaction to a foreign body, and is likely to settle. If the pain is sever or if you cannot feel the "thread" please consult your gynaecologist personally or go for an ultrasound
scan to make sure it is in its correct place as displacements of coil may also cause such symptoms. If you are really fed up; you have two choices either request your doctor a birth control pill for few months along with the coil, to let everything settle & don't forget to take a haematenic along with it, if your Haemoglobin
is low or choose another method of birth control. Take care.