Talk to Gynecologist on Double Period In 1 Cycle

i had a 30 days regular cycle.i had a chemical pregnancy in feb 2018 since then my cycle changed to 40 days but in every cycle after 30 days i have a short term periods in form of spotting of light bleeding for 2 to 3 days and then on 40 to 42 cycle day i have my regular period i am so worried and also trying help me. i had pcos too.