Hi! I have similar symptoms to yours, and all tests have come back negative. The probability of your having ALS is very small, so please don't worry about it.
If your EMG/NC and MRI (brain? upper cervical?) are clear then a lot of potentially unpleasant diagnoses can be ruled out. Likewise, seeing your blood tests are clear for autoimmune diseases is good. Was your blood also tested for Vit B, Magnesium etc?
Despite not diagnosing the problem, I was initially prescribed pregabalin but stopped after a week due to side effects. I then started on amitriptyline, and 50mg/day mostly masks my symptoms (occasional tingling/numbness & very rare twitching). Other than some tiredness when starting the amitriptyline, I tolerate it very well.
I'm currently seeing "NUCCA" chiropractor, and after some sessions my symptoms have eased but I still have a way to go before I feel "normal" again.
Same thing happened with me, but with Numbness, I also had some unusual muscle/nerve pain which comes and go randomly anywhere in the body. That pain felt like different from all the pain I had experience before. This started unusually before 3 months after a very stressful weekend.
I also did EMG, NCV, MRI, 100's of blood test, urine test, ECG, Stress ECG, Doppler ECG, XRAY. Everything came out normal except my Vitamin D level. My Vitamin D was 13 , recommended is 32-100 I believe. I started developing twitching constantly whole body non-stop since last month which hasn't gone yet. Although after taking Vitamin D pills with Muscle relaxant by unusual random pain went away mostly. But twitching is still there. To be double sure, I did magnesium test and it came normal.
Have you checked Vitamin-D ? Its deficiency can causes all this
I've been twitching everywhere, and. I mean everywhere, for 3 months. Have an EMG Tuesday. Check B6. If you have to much it can cause neuropathy. Probably only if take supplements.
Wondering how you're all doing now? It's 3 years since the onset of my symptoms. Things got MUCH better, and now I'm more or less OK, with a flaring up of nerve pain in some areas, and tingling in my face, if I get particularly stressed or angry.