It can be from neuropathy and statins. I found that taking co enzyme q10 made mine go away. I also take alpha-lipoic acid and acetyl-l-carnitine and these all play a part. Some say magnesium or pickel juice but I figure that just deals with symptoms and these supplements help nerves. I'm basically neuropathy free along with type 2 free since doing low carb and intermittent fasting.

I take a product called calm it is a form of magnesium that get metabolized readily . Helps my cramps and restless leg.