Depo Provera, Pink Bleeding.

So as stated in the topic, I am experiencing some pink bleeding on the depo shot. I started bleeding 3 days ago with some minor cramps, but now the blood is a pink color. I have been on the shot for almost a year now. And I am definitely not pregnant. I was just wondering if anyone else has experinced this before and could provide some insight. I also haven't had a period in a few months just some spotting occasionally. Any answers would be helpful. Thank you.