Not sure what to tell you, sweetie. I'm not an expert on this, all I remember is what I learned about hormones and birth control.

Sometimes if our hormones get messed up it changes the shape and solidity of the cervix, which then allows blood to pass through.

Since this is the very first time this has happened to you, it's worth checking it out. The doctor may have you come back when you're not spotting a lot to do a pap smear. If you're not cramping, nauseated and experiencing a fever I doubt it's anything serious, but it never pays to take chances with your health! Plus the only way to set your mind at ease is to have a definitve diagnoses. :) So the peace of mind is worth the time and cost. :)