For a long time I have suffered with appalling leg, feet & hand cramps. So bad my feet & hands will lock up and the cramp will go on as long as 15mins. I tried magnesium supplements and they helped a little but what I have found the greatest success with, and accidentally, was amitriptyline at 25mgs a night. It takes I think a couple of weeks to become effective and also solved the night peeing!!! It may be worth talking to your onc about it.
I did take magnesium supplements years ago (advised by a nutritionist) 2x 150mg a day. I stopped for a while but have recently started again after reading up about magnesium. I read it takes quite a while to build up the the correct level as a lot of it isnt absorbed. The book said as long as 2 years! I’ve just started reading about taking it transdermally and have bought some magnesium oil which is a super saturated solution in water so not really an oil although it feels like it. It supposed to be faster tissue absorption and takes up to 6 weeks to get the optimal levels.
I also suffer from leg cramps,mine is a side effect of Tamoxifen.
Will get it twice on the same leg and soon if i am rid of this the other leg start to cramp,this is so sore i could not walked.So two day`s after this cramps,my hip and buttock starts to pain.What helped for me i take Magnesium&Zinc tabs with Plenish K salt tabs and vitamin D3 tabs and eat a lot of bananas.