Implantion bleeding

So glow said I should get Mensa yesterday and I didn't but I also use period tracker because glow never gets my period right because I have pcos. I am am mother Of 3 kids all teenagers and had 4 mc in 1 yr so my period tracker said I should get my period 9/19/2015 but glow said 09/12/15 so the crazies thing is I go to bathroom and my mens is all dark Brown never happy before my back is killing I my stomach is to I don't get Mens cramps I never did but this is all new to me so I was think implantation bleeding I got one more thing my nips hurt i hope this is what do y'all think