I've suffered with foot and leg cramps my entire life. When I started the low carb diet, I began having cramps in my chest too if I bent down to tie my shoes. I take 450 mg magnesium citrate. I don't remember how long it took, perhaps weeks or a month, but once the magnesium began working, it worked great. For the first time in my life, I don't have cramps.
I also upped my intake of magnesium plant based foods.
Hope you get relief soon.
By the way, are you taking a CoQ10 supplement to rebuild your CoQ10 levels? (Statins block the pathway that create CoQ10. Your cells use CoQ10 "to produce energy your body needs for cell growth and maintenance. It also functions as an antioxidant, which protects the body from damage caused by harmful molecules.").