Hello, If you are sexually active, then you must undergo one home pregnancy test to exclude early miscarriage. Other reasons of painful late period may be hormonal imbalance, endometriosis, pelvic infection, fibroid or polyp, adenomyosis etc. You may need to undergo one USG scan and hormone test to rule out underlying pathology if any. Proper treatment can be made after diagnosis. Kindly, consult with your gynecologist regarding this. In the mean time, you can take combined tranexamic acid & mefenamic acid to get rid of this kind of problem. Maintain genital hygiene. Good luck.