LMP started 08/30/11 & ended 09/02/11, 27 day cycle average, next period is not expected until 09/25/11. Expected ovulation 09/11/11. Unprotected sex 09/11/11 & 09/12/11. Light pink spotting started yesterday evening (09/14/11) with mild cramping & headache , put a pad on overnight and upon waking this morning there were 3 or 4 spots of brown. Today (09/15/11) put new pad on this morning bleeding is darker pink, almost red, see it when wiping and dripping in toilet when sitting on toilet (after/during urinating), have not had to change the pad today (nothing at all on it). I have had frequent urination about once an hour for the last two days. Still having mild cramping, comes and goes but no headache. Have had a metallic (blood like) taste in mouth a few times today. Could this be implantation bleeding? miscarriage? midcycle bleeding? (pregnancy history= one partner- prior successful pregnancy 10 years ago, one miscarriage 8 years ago @ 11 weeks, successful pregnancy 8 years ago; second partner- one miscarriage 4 years ago @ 6 weeks and one miscarriage 6 months ago @ 4 weeks; new partner now).