What Causes Inter Menstrual Bleeding?

I am 44 years old. MY period was to start next Thursday, but for some reason I bled this past Tuesday night and was done by morning. Am I going through the change of life, or is my monthly just getting ready for it? I have not bled since, I cramp or feel like I am passing clots, but nothing shows up. Should I just wait for my normal start date that is next week? Thanks, Elizabeth