Episodics are the normal method of suffering from this condition.  By episodic, it means that you suffer for a period of time.  It could be a few weeks, a few months, or even several months, and then you go into a pain free period that can last up to several years, before starting another cycle.  Most have 3 to 18 months pain free between cycles.

Chronics never get the break.  I think the definition is either one week, or one month, continuous, without a hit, classifies you as episodic.  If you don't have that, you are chronic.

There are plenty of theories as to the cause of going chronic, but none of them have been proved.  It is just another unknown entity to our condition.

Chuck