Miscarriage?

I am currently on the depo, and I've NEVER had a period on it ever in the 9 months of having it have I ever once bled, until yesterday, I have been very very stressed latley, and I was having very bad cramping and back pain, I've also had a lot of clear slimy discharge along with the bleeding. So I looked up my symptoms. I don't want to freak out but I also know before my most recent depo shot I WASNT tested for pregnancy. I just wanna know what's going on with my body, has anybody had anything like this happen?