I Am Currently On Birth Control, But Have Not Been

I am currently on birth control, but have not been consistent with it. I recently had some spotting and as I was taking a shower I noticed pieces of flesh coming out. Is this a sign or pregnancy, an infection? What does this mean im 18 and in college. I'm stressed that I may be pregnant or have a disease and I don't have the money to treat this. It would be a great deal of help for you to explain to me what is going on.