I still have serious pain from a leg amputation that I had 5 years ago. Can anyone suggest any pain relief?

Phantom pain. You are likely suffering from phantom pain, a syndrome that afflicts patients after limb amputation. The syndrome is poorly understood but you do have some treatment options. You should seek a pain specialist with experience treating this syndrome.
Depends. The pain from an amputation after a few years could be from a number of different problems. You need to be evaluated by the surgeon that did the amputation. There are options for this and you do not have to be in pain.