The basic problem is: What do you do about a chronic condition for which there is no proven treatment? I have a few people in my life with one such condition or another. There are three responses, mostly unhelpful.
The most common response is to essentially suggest things at random. Both rest and (generic) exercise are common suggestions. This can make the patient happy, but it's often actively harmful -- obviously, both rest and exercise won't help the same thing, unless it's a specific exercise chosen with the condition in mind.
The other common response is to not suggest anything, and basically try to get the patient to go away. If you're lucky, they'll try to sympathize, but mostly you'll just get brushed off. This makes the patient feel bad, but at least it won't actively make the condition worse.
The response you'll get if you're really lucky, is that they'll refer you to participate in a study of some kind. This is lucky because it's very high variance: it could kill you, but it also could significantly improve things. Obviously that risk isn't for everyone, but it's lucky to even have the choice.
Unfortunately, without a proven treatment, there isn't a lot else for doctors to do.