My period started today really heavy and its 10 days early. What could cause that?

Possibly pregnant. Take a home pregnancy test. They are reliable, accurate and valid. If it's negative, repeat it in one week. If it's still negative, see your doctor.
Possibly pregnant. Take a home pregnancy test. They are reliable, accurate and valid. If it's negative, repeat it in one week. If it's still negative, see your doctor.