My period came on october 15-22 and came back on october 25-28 and now now i'm just cramping and spotting. it's never done that before. what is it?

Pregnancy possible: The possibility exists. If you are one week late and still haven't had your menses, you should perform a home pregnancy test. If it is negative, repeat in one week.

Need evaluation: I would recommend following-up with your gynecologist for an evaluation. The differential diagnosis is varied and more info which could be obtained without difficulty at a doctor's visit would be helpful - menstrual history, age, pregnancy test, meds, etc.