I have had it for over 15 years. There are no definitive causes, but stress can cause it as well as other things.
According to my research, there are two main types....one is situational, in which there is an episode, and then gradually either the episodes decrease or increase, dependent on the person and the situation...in my case, this was my category.
The other is much more serious and debilitating, and episodes maintain their presence, and continue over time. Some famous actors have had this (Annette Funicello, Richard Pryoer) and though I dont know for certain,they seem to have the second category.
I had no insurance when initially diagnosed, and luckily received help through a support group, where I found that diet and exercise helped my symptoms. Unfortunately the damage caused in my case only was a lack of feeling on the right side of my body down to my knee, along with debilitation in nerve endings that calculate need for bowel movements, and withstanding heat and cold....all of which I have cmpnsated for without using drugs of any kind.
I am extremely lucky in this regard, andjust have to stay away from certain foods like meat and cheese, in order for the symptoms not to appear again.