Period for 5 days light red and watery then spotted for 5 day nothing for 3 days now heavy bleeding and clots? negative preg test 3 days ago

Cycle changes: This may be due to hormonal variations, stress, tension, anxiety, illness or spontaneous abortion if you had been having unprotected intercourse. Please consult your GyN for a pelvic exam and testing.

See doctor: There are several things that can cause this. If you are having heavy bleeding now, you need to be seen to be sure you aren't getting anemic and address the cause before you do get anemic. A full history and exam with appropriate lab testing is needed. Best wishes.