My periods have changed. when should i see a doctor about it?

Specific changes.: Periods often change becoming longer or shorter, heavier or lighter, or with differing intervals. As a general rule, you should check with your doctor for menses consistently less than 20 days apart from beginning to beginning, bleeding longer than 7 days or bleeding and spotting longer than 10 days, unscheduled bleeding or spotting between menses, or bleeding heavier than 1 pad per hour.

Menstrual changes: Not sure how your periods have changed. See that you are 50 years old. If you believe you may be perimenopausal - your gynecologist/ physician can help to determine if this is the cause.