Black, brown discharge. My period is 2 weeks late.

hi, i had my period about 2 weeks ago but it was as long a 4 weeks i think this is because i recently had my coil taken out, i went strait onto the mini pill and now the last 2 days im having this black/brown discharge and it is quite alot i also had a swab done when i had my coyl out i had the results back and it said i had to be retested in 6months in stead of 3years it was because of abnormal cells. is this why im getting the discharge because of the abnormal cells? i dont understand what is happening the abnormal cells leflet just kept going on about cancer is this right ? have i got cancer ? help please someone????????