Had mirena coil fitted march 2017 now having period/bleeding for the first time since. coil still in place smear ok no change in meds, weight, health or stress what could be causing me to have a period/bleeding after 2 and half years?

A few possibilities: Most possibilities are not likely cause for alarm; they include perimenopausal changes in your ovarian-pituitary hormones or some local changes in your uterine lining; you are probably not pregnant; it is unlikely that you have a uterinae polyp or lesion. A gyn evaluation, pregnancy test, pelvic sonogram may help answer your concerns. The bleeding may resolve spontaneously and remain unexplained