I was diagnosed with PMR around Feb. 2017. Over that time my hand cramps, especially in the left hand, have got progressively worse, so I did a google search and as a result started reading all about how good a cake of soap was at preventing cramps; don't know how it works, but it has for me. Just holding a cake of soap for a few minutes and the cramps have not come back. I now leave a cake in my bed between the sheets for leg cramps. Apparently it does not matter much, which brand you use, but its power to make a difference does diminish and needs to be replaced. May not work for everyone but worth a go! A piece of cork in the bed is another remedy that I have found works.
It would be interesting to know if soap has any effect on PMR pains, any feedback on this appreciated. John