There is not much difference between CFS and FMS. Several research studies have been done, to try to determine if they are the same or different illness. And they have all found the result is they are NOT different illnesses.
BUT among certain groups of both patients and Drs, it is a hotly debated topic. There are a LOT of people who aren't convinced they are the same illness. And with such a complicated, and as yet mysterious illness, who's really to say exactly (at this point).
So to answer your questions--the difference between CFS and FMS (on the assumption they ARE different) is that with CFS the major (or most common) symptom is chronic fatigue, and with FMS the most common symptom is chronic pain. After that, they are identical. And again assuming they ARE different, yes one can have both CFS and FMS. And yes, one can have one and then get the other later.
Have you found the FMS forum here at HealingWell? It is much busier than this board, although without a moderator at the moment. You can find support and information on either board, but probably more on the FMS board, at the moment.
Anyway, thanks for "stopping by", I'm glad to meet you. Please feel free to post as often as you want or need.
Moderator for Chronic Pain forums and
Chronic Fatigue Syndrome forums