@j77
How very frustrating and scary for you. MG was the first thing that came to my mind when you said it wasn't ALS. 6-12% of people with MG test negative. Could you be one of them?
https://www.mda.org/disease/myasthenia-gravis/diagnosis
I thought I had ALS 9 years (I was 56) ago when I was suddenly aspirating everything I ate. Very scary! I couldn't control the food in my mouth and it would slip down my throat before I was ready and led to violent coughing fits. I lost 25 pounds in a month from not eating since I had aspirated 50 times in 3 weeks. That sent me into afib. You can get pneumonia from aspirating too. Food also gets stuck in my throat sometimes and it's all based on chewing fatiguing my muscles. If I try to eat salad or other foods that strain chewing muscles, I'm really going to have a bad couple weeks coming up from chewing/swallowing muscle fatigue. I was tested for MG and didn't have it.

My neurologists also ruled out MS and ALS. It was determined the swallowing issues was related to a rare hereditary neuropathy I have that falls under the CMT umbrella, but less serious. At times, I also get muscle weakness in my thighs, arms and neck, but not to the severity you have it. I have had major issues with muscle twitching since my 30s or earlier. Issues with numbness since my teens. Also pain issues. So I believed that the swallowing was in fact just a new issue with the same neuro condition. I recently had to drive for hours and the next day I could hardly lift my arms from muscle fatigue. It's a pattern. My son inherited the condition too and says if he lifts something heavy one day, his muscles are very weak the next day or two. He doesn't have the swallowing issues though, but that hit me later in life.

Bottom line, the neurologist that did my testing suggested mestinon a year or so later when suddenly I was even aspirating liquids. It makes perfect sense since when I read about MG, it sounds like my issues, just from another cause. Worth a try for you especially since you'll be treating the symptoms regardless of the cause. I didn't try it only because I never seem to do well with meds and have extreme adverse reactions so I have a fear of trying new meds. I also know a lot of people get severe diarrhea from mestinon and I felt like I'd rather deal with my swallowing issues. Maybe you'll do well with mestinon. I've learned what not to eat which is most things. Makes it hard to eat a healthy diet. I also keep my head tipped forward to help keep me from aspirating. Mindful eating. I still have the same issues 9 years later, but still at about the same level, gets worse at times, but then goes back to the level I started with 9 years ago. It has never improved from 9 years ago. My legs have massive twitching going on as I write. I'm used to it. At times, my toes act like a player piano.

If your symptoms all started with COVID, I would not be surprised since I've heard people having every possible crazy reaction to that. Seek out another neurologist if you're not happy with the one you have. A neuromuscular specialist would be ideal. Just know there are other causes to all your symptoms than ALS so keep the hope that a solution is out there for you. And if it was caused by COVID, maybe it will go away altogether one day. Prayers for you.