Bleeding

Ok so I have pcos and I had my son March 2014. My period was always regular same time every month 4 days a month, then it completely stopped Aug. 2015 then Aug. 2018 comes along and my periods start again regular as ever then December nothing Jan Feb march they were regular April no show then May it was Regular June it was a no show and then July 27th came along and i started spotting. July 28th I started my period and ive always had my periods for 4 days but since i started on july 28th my period is still going it was only heavy one day but its been light/medium. I dont understand why my period is lasting this long. It never has before!