irregular periods

Dr Soriano I am 37 years old, I have 3 children my period was regular until 7 months ago it was delayed for 14 days , in the doctors check she found a small (0.26 m"m) prisistent cycst in the right ovary since then the periods were regular every 25-30 days last month the period was delayed for 18 day and the nest period was after 13 days My questions are: Is this irrgular periods are deu to the cyst or is it because of my age What can be done about it thank you