I am on birth control and I do not take it regularly and my husband and I don't use protection.I always get my period on the Monday I start my green pills. This time I didn't get my period so I thought maybe Tuesday still no sign and then on Wednesday I started to spot really dark brown but very little and my period is normally very heavy and I have really bad cramps. Well it is now Saturday and I still only have a very small amount of dark brown discharge with no cramps at all. Could this be implantation bleeding??