Are my symptoms related to hypothyroidism or myasthenia gravis?

[Caprice123]

I displayed symptoms of MG, but tests proved negative. I am 76 years of age and I did read that an expert Professor of MG in Canada, says that elderly people do not always test positive for MG. Usually, their symptoms start with speech problems, as in my case. I was unable to communicate effectively, for some 9 months, then my clarity of speech returned along with my swallowing ability. I am still breathless and my facial muscles can weaken from time to time. I did read that elderly folk usually show signs of bulbar symptoms as well. I still get very tired, so I do what I have to do in the mornings. I know that MG is an immunity disease, so I am on a gluten, dairy, sugar, caffeine free eating regime, hoping that my immune system will calm down as I am plagued with allergies all over my body as well. I also take Astragalus, a herbal supplement for the immune system. My question is, can the severity of MG symptoms come and go? My speech declines if I am very tired or stressed out. Bed rest for a few days brings it back to normality as with the swallowing. I am hypothyroid and wondered and hoping that my symptoms are more hypothyroid than MG. I also now have, atrial fibrillation, permanently.