Early Period or implantation

Has anyone had an early period around the time you would get implantation bleeding?? i started off with brown discharge and then next day it was pinkish, 3rd day nothing 4th day a little heavier red blood and 5 back to pinkish discharge then nothing... this happened a week before my period was due. then my af never came on its due day. i have been feeling nauseous and getting slightly mild cramps on one side.. took 2 hpt tests last week and BFN do you think i should test again a week after period was due. my cycle has always been 28 days without fail. so this has come as a little shock. any help is appreciated.. baby dust to all