I have to agree about the cause and cure still eluding the medical profession. I have fibromyalgia which makes your muscles fatigue and cramp very easily, as well as ME/CFS which does the same, so add to that Oesteoarthritis for the bones and joints and you have constant pain or one type or the other.
I have been tested to pin cushion stage, have eagerly swallowed everything offered, including, Quinine pills and antimalaria pills for 3 months.
Nothing helps, I still have night cramps all over my body. I have tried less salt, more salt, less sugar, more sugar, every internet option.
I usually stay up at night doing as much as I can in the way of housework, walking around the garden and try not to sleep, that way by the morning I am exhausted and go into such a deep sleep for about 4 hours that I feel nothing.
Please let me know if there is a cure. "currently cycling 2 miles per day, at 4mph". Cycling 2 months now, and it hasnt made it any better or worse surprisingly.
One tip to add, bring your toes up towards your knees when you stretch, NEVER point down, that is how I avoid calf ones.