What Causes Cramps In The Thumbs And Cold Feet?

Hi...I have been off chemo for about 15 mos..recently,my hands turn into claws,my thumbs cramp and go almost all the way across my palm and I literally can barely pry it away..my feet cramp,my abdomen and belly cramp sometimes and I have to stretch hard to make it stop.It s scary sometimes..I believe I drink enough and take enough pottassium..I m 77 yrs old..fairly active.My hands and feet get very cold..also I have mild neuropathy in hands and feet since the chemo.The tops of my hands,forearms,shins just ache sometimes.