Muscle pain can be, as in your case, a significant issue for people with CFS/ME.
People tend to find it may have a generally constant impact, but gets worse:
1) When being 'over-active' - ie doing more than the body is entirely happy with
2) When resting too much, or being 'under-active' as the muscles weaken considerably making it much harder to do things.
So, how to improve things?
One thing you can do is to keep a diary of your physical activity and compare this to when the pain is:
a) worse than average
b) better than average
This can give you some clues as to what the 'right' or 'more comfortable' activities are, and how you can adjust activities accordingly to gain more stability.
Whilst it may feel difficult and painful, there is no evidence to suggest that the muscle pain associated with CFS/ME is as s result of any harm being done to the muscles themselves. What we do know is that things can get worse if activity is reduced, and where the overall levels of activity remain low.
It is also thought that poor sleep can impact muscle pain, so it is also worth looking to address any sleep difficulties there may be. Muscle tension can also play a part: so actively undertaking regular relaxation and meditation exercises can also help the muscle pain. 'Mindfulness' and 'body scan' exercises can be particularly helpful.
Ultimately the muscles need to move, and to gradually and carefully build more muscle fibres to improve this longer term: this means gradually and carefully doing more over time, whilst staying at a level at each small increase until the body has adjusted.
Some people also find gentle stretches can help, and warm baths can also improve circulation and help muscle comfort.
Please note that this post does not constitute as individual therapy advice: individual advice should be sought on a one-to-one basis with a therapist
BSc (Hons) Physiotherapy, MCSP, PVRA, HG (Dip), MBACME