How about Fibromyalgia?
Hmmm this one is tricky.
This particular ailment isnt curable, rather you deal with the symptoms.
The fatigue and aches will be a rough combination, but most specialist recommend physical therapy to increase stamina.
While I'd simply say excersice should help, aquatic therapy might be the better route.
Out of all ofnthe water types, I would actually recommned Siesmatoad.
They are good swimmers, but their vibrations might help with muscle relaxing and blood flow through the body, which could do good for lessening fatigue.
Its also a way to get muscle relief without the worry of pressure and pain from a massage.
This in combination with medicine from your doctor and maybe an occasional visit to a Croagunk specialist.
Ultimately it will be up to you and how well you keep up with your therapy, but a Siesmatoad might be a solid choice for the help with aquatic therapy alone.