Implantation bleeding?

So Oct 10th I had sharp lower back pain and cramps and I began to have pinkish discharge. The next couple days nothing. Oct 14th I was walking to my lunch break and I started to have a sharp cramping pain and quickly went to the restroom and I had pinkish discharge again. Has this happened to anyone else as well? Im confused. I did get off my bc in Sept and already had my withdrawal bleeding. I know it takes time for our bodies to go back to normal. So is this normal? Before I call the doctors.