i have all those symptoms and atrophy and i DO NOT HAVE ALS...you can have cramps, exercise intolerance, weakness, random constant twitching, burning, numbness and tingling with peripheral neuropathy or any injury to the nerves...you don't necessarily have to have slow SNAPS to have it (abnormal sensory nerve conduction) it can show up as a motor neuron dysfunction...i totally understand your worry as i have been living this nightmare for four months, please talk to your neuro...ask him/her point blank if you have a motor neuron disease...and if he says no, then ask, WHAT IS IT?
ALS is extremely rare...there are MANY things that can cause these symptoms including hernias, sublixations in your spine...doctors just don't seem to understand that waiting for answers is cruel punishment to patients (patience)...but, sometimes that's all we can do is wait it out...in the meanwhile, i asked for physical therapy and medications to reduce my ridiculous pain...it helped me and maybe good for you?...good luck