I Have Pcos But My Period Is Unusually Regular For

i have pcos but my period is unusually regular for a pcos sufferer. I'm 37 had my 3rd child 14 months ago, period returned normally last January when I stopped breastfeeding but for the past 7 weeks I've had a nearly constant periods. Starts for 3?weeks stops for a week and starts again. Why is this happening and what could I do?