Itchiness is my most characteristic symptom - and over the years I've found that when I'm itching badly, my other (more typical CFS) symptoms are much reduced. This appears to be due to a complete vulnerability to any kind of molds or spores, and I seem to pick stuff up on my clothes when I go out and sit on the wrong chairs, especially in places like theatres. I've recently found that it's normally something specific I'm wearing that sets me off, but it's really hard to track down because the itching is all over my body, not particularly at the place where I'm in contact with (wearing or sitting on) whatever's setting me off, even when it seems to be localised.
The only advice I can give is to pay attention to possible food sensitivities (not necessarily allergies) which can be cumulative (and thus hard to work out without testing) and to keep trying different clothes, bedding etc (also washing powders are very provocative, I use washing balls, never powders, especially not biological powders) although brand new clothes frequently give me very strong reactions as soon as I try them on. Deep experimentation, and establishing an 'oasis' of reliable safety from reactions, are vital. An air filter (HEPA filter) is also vital to remove spores etc from the air of course.
I don't know, of course, whether my syndrome is XMRV, CFS, or an unrelated sensitivity to multiple allergens, but the above are my characteristic symptoms of 15+ years. When I itch all night (disrupting my sleep) I quickly start to develop the other symptoms of CFS; my sleep is unrefreshing whenever I'm in this state, even when I can sleep. Focusing on reducing/removing sources of itching, over the years, has improved my other symptoms more than anything else. But it may also have been improved by things like Di_ribose and all the other supplements I've tried over the years. I eat an extremely restricted diet too, which seems to have helped.
The weirdest thing is, I appear to infect everything I wear within about 3 days. If I stay in a hotel, on about the 3rd night the sheets and pillow start to make me itch (assuming they didn't do so on the 1st night). I have long suspected that I'm sweating out some toxin onto sheets and clothing, and wondered if I'm unusual in being able to feel the re-infection physically.
I'm also now wondering whether it's the pathogen itself (eg fungus-embedded XMRV) that I'm sweating out...