Help

Took a month off of clomid for August... Period came on August 12, which was mostly spotting. Barely enough for a pad. Pregnancy test was negative. Well last night I noticed blood after using the bathroom and wiping. Not a lot and was gone this morning only to return a hour or so ago and a little more. I am not due for a period until the 11 or 12. According to my ovulation calendar if I had a fertilized egg it should have made it to my uterus yesterday. Could the bleeding be implantation bleeding or a my period coming early?