What can cause muscle pain, twitching and atrophy in the arms and legs that is worsening in less then 1 years time?

Muscle Twitching: Biggest concern would be for a motor neuron disease. An example would be lou gerhing's disease or als. I would definitely have this evaluated. Start with your primary care provider, a neurologist, or physiatrist.

Several things: I would recommend you seek the attention of a neurologist if you are clinically suspicious or seeing these problems. You could have something neurologically going on.