Hi I am 46 years old, I am on my 3rd period in 3 weeks this is not normal for me. What could this mean?

See your Ob Gyn. You need to see your OB gyn for probably an exam, sonogram and possibly an endometrial biopsy. There are a number of things which could cause this, as well as a number of treatment options. Good luck.
Starting Menopause. At age 46, this could be perimenopausal bleeding. I usually have patients get an ultrasound of the uterus and check hormone levels. Another cause could be thyroid disease. You should see your doctor for an evaluation.