I have fear of having disease like als. i have fatigue in arms and twitching in calves but i have neck pain and don't sleep enough. should i worry?

No: ALS is very unlikely. Chronic anxiety is more likely the cause

Systemic disorder: 38 yo male w. insomnia, "neck pain, fatigue, arm pain & calves twitching" fears ALS. A general medical evaluation is indicated & by a Neurologist. If no specific diagnosis is found, then Fibromyalgia might be explanatory. A Rheumatologist can evaluate for Fibromyalgia and prescribe FDA approved medications for this disorder, which is a diagnosis of exclusion.