Could Brown Discharge Be Menstrual Blood Or Implantation Bleeding?

Good Day Doctor (s)I'm from South Africa, healthy 29 year old, I do smoke, but very little. I was on birth control for about 13 years and have been of it since December 2010. Hubby and I have been trying to conceive since. I have a 29 day cycle, and this month I started my period 3 days earlier (on Sat eve, when only suppose to start Tuesday eve) Only had it for a day and a half and it was pinkish light reddish blood. Now 5 days later I have a slight brown slimy discharge. Is this just old blood from my period or is this implantation as it is when I'm suppose to have my period? I also have slight cramping and like a cramping in my leg?