I have been having headachs, abdominal pain, and a little more dischare than normal. Is this my period coming? This is what my mom said it might be I don't know for sure. I'm turning 13 in a week if that helps.

Sexual activity? If you are sexually active, you may have a venereal disease. If not, you may have a vaginal infection. If this prodrome is different than what you normally experience with your periods, chances are it is something different causing the symptoms.
Yes, . Yes, that is a possibility. If your symptoms are severe though, or if you have new symptoms such as worsening headache or vomiting then you must be seen right away by a doctor.