I have had 3 periods within a month and they have all been heavy bleeding and clotting

Anything that deviates far from the 28 day normal period is indicative of a problem. Contact your GYN or Physician ASAP... just to be safe.

This is the same position I've been in but my periods have been non stop for 3 month, if you get any advice please could you let me no, thanks :)

Smoothy gave the appropriate advice - see a Physician.