Hey man - I am a 27 year old who went through ALS anxiety. I also had muscle twitching a upper arm fatigue/burning pain. Good note is pain isn't associated with ALS and twitching is usually found as the muscle is dying. Once twitches start, they don't stop. I went through the EMG testing and nerve conduction and it came back normal. An MRI showed i had neck arthritis and bone spurs that were affecting a few nerve roots in my neck, causing these symptoms. So, it sounds very unlikely but the test that will put you at ease is an EMG.