It has now been a little over a year since your post and I hope that you have found some answers. I thought I would give you an update on myself in case it could be relevant to your situation.
My symptoms of muscle weakness and stiffening since my note to you had only worsened and my doctors were not able to get anywhere. By the fall I was beginning to very noticeably feel brain fog and an inability to think clearly, which was quite scary. It is quite a long story and I will try to be and be as concise as possible. Through research on neurodegenerative disease, quite miraculously, I kept noticing "glutamate" coming up. It is an amino acid found throughout your body in abundance, and is also one of the most predominant neurotransmitters in the brain. Many people are deficient in this who have gut issues, but after further research I learned that people who suffer from neurodegenerative disorders typically have elevated levels of this amino acid in their brain which can cause a problem with movement when not kept at a regulated level in proportion to other neurotransmitters. An article written by Dr. Vikki Peterson, who specializes in Celiac Disease, states in an article that people who suffer from Celiac and a neurological manifestation of Celiac, may also have a problem with dietary glutamate. Glutamate is found in all food, but especially processed food, and high protein foods such as beans, nuts, meats, dairy, also anything that is cooked for long periods or fermented like tomato sauce, bone broth etc. After trying a half a block of Parmesan cheese which has a particularly high level of glutamate, I noticed that my leg stiffness and weakness worsened terribly. After two weeks of giving up high glutamate foods my symptoms resolved. The day I didn't even know I could walk (well) I ran!! It has now been four months and I am feeling better than I have in years!! I am keeping a very careful diet and trying to vary things as much as possible, and keeping very careful proportions... But I am thriving. I do not eat anything processed except for an occasional rice cake and a little almond butter. It is not easy-- but I have my life back and can keep up with my kids.
This information on glutamate I think may may be something to consider for anyone who is suffering from any form of a neurodegenerative disorder-- from MS to autism and ADHD. It is very interesting and something is that many in the medical profession are not aware of. My doctors say that I'm a walking miracle.
I hope that you are feeling better and have found some answers! I don't know if this could be helpful but thought I should let you know in case it possibly could be.
@cmmichaela Have you found a list of high glutamate foods to avoid?