Question: Implantation bleeding?

Hello all, I am on CD27 of a 32+ cycle, I had a spot of pinkish blood on the tissue when I wiped (tmi) on CD24, spotted brown on CD25 and yesterday I was getting brownish blood just enough to wear a pad. I am a week early which has never happened to me before as my cycles are 32+, last month was 50! I have took two PT's which looked like very faint positives but I am not sure. Also having cramps and backache and I have put near enough 8 pounds on in the last three weeks. Is it possible I am having implantation bleeding or an early period? Is it possible to have a very faint positive this early?