The back of my left calf above my ankle is very itchy and my toes feel numb while laying down in bed. i read an answer about hot bath can be the problem, i wonder if it's that or lack of exercise?

Either: It is not feasible to provide a meaningful opinion without taking additional history, physical examination and may be some tests. It would be prudent to see your doctor and discuss if you may be depressed. Counter-intuitive as it may seem, exercise may help. Start with low intensity exercise such as walking and gradually increase the intensity as tolerated. Wish you good health!