Tmi! Please help!

Starr • Mother of a baby boy, married to his daddy.
What is this?! My son is 2 months old and I have been spotting for two weeks until last night, I finally started bleeding heavy and cramping bad and having back pains today. I went to the bathroom and this fell out! I'm on birth control but we have had unprotected sex several times but I don't think I am or was pregnant. I need help please!