Rach,
Print things about MG off the computer and bring the tensilon results with you and explain that ANY improvement from the shot is noteworthy. DO NOT give up and explain to the Dr. that you will not tolerate being told it is mental "as we ALL have been told that by one Dr or another" You are a strong person and I know you will be able to do it. My question is, why is your Dr. so against it being MG, as him that and see what his answer is. as your GP he should be happy to send you to another Neruro. I don't understand why he is being so bullheaded. But like I said ask him "why" he is so against it. Please let us know how it goes.
Big Hugs