20 Day Long Period

Lizzie
Hello Ladies
I suffer from PCOS and I have very irregular periods. My period started around 18 days ago and looking like no signs of ending soon as still very heavy and clot try ( sorry)
The last period before that was in September. 
Due to it being so heavy and very clotty like really horrible nasty big ones is this something I should be worried about or is this just a normal but long period?
Thanks ladies xxx