Ask doctor why? Muscle wasting is seen with neurological problems, lack of exercise, aging, and when it is symptomatic, evaluation should be completed. When your doctor suggested that to you, the next question you should ask, "why doctor? ".
Will doctor operate if both arm and legs are weak astrophy and wasting away even stomach muscle is weak do to a compressed spinal cord or pinch nerve?
Yes. If weakness is due to spinal cord compression, that compression must be relieved on an emergency basis to prevent paralysis. Surgery may be used for that.. I think there is essential information not being shared with us here.
Muscle on calf is wasting away and soft lump is developing, what is it and what kind of doctor do I see sbout it?
Muscles do not. Normally "waste away", particularly if the muscle is still in use. So an elderly bed ridden patient may get muscle wasting because they no longer use the muscle. If that is not the case you need to see a doctor. Any lump needs to be evaluated by a medical doctor. I think a good place to start is your internist.