multiload coil and lactating heavy

Hi im a little concerned about lactating as i have the coil in and it was put in jus a day before my period was due so i only had light staining after it went in and missed that period then had my usual period the following month a little late like a day or two and its been on the heavy side lasting a little longer and i am now having blood staining and dark daischard a week later and my breasts are heavy and sore and have been for a while and lactating very heavy im concerned im pregant i have 3 kids already so kinda know the signs but these are a little different my youngest is 11 months and i breast fed her for 3 weeks and the milk had completly dried up and now its back very heavy please help as its worring me incase im pregent with a coil in, any advice would be great