Period while breastfeeding?

Michelle
My son is 3 months old and is exclusively breast fed. I had my tubes tied about a month ago. Give or take a week. Two days ago I started bleeding, after hubby and I had sex, very dark red blood. Its not enough to even really need a pad but it's there when I wipe and quite a bit of it. I thought EBF moms didn't get periods until they stop breastfeeding? I don't have an appointment with my OB for like a year and they're booked up until the end of September anyway. Did the tubal cause my period? Or did something happen. Other than slightly crampy and exhausted I feel alright. Do you think it's my period or should I go to the doctor. I have never had this happen before, and based on what I thought I knew I'm very confused. Any thoughts are appreciated. Thank you!