I'm sorry you have so much going on.
I'm not sure if a TNF blocker would affect the AChR antibody blood tests or not. Did they do the MuSK antibody test?
A primary care physician is not qualified to diagnose asthma, which, as you said, was probably a misdiagnosis. You should really go see a pulomonologist and have extensive breathing tests to determine what is causing your shortness of breath.
A pulmonologist can do regular PFTs, plus Maximum Inspiratory Pressure (MIP) and Maxiumum Expiratory Pressure (MEP). They can look for trends in the readings, as well. When someone with MG is doing poorly, the numbers tend to decrease with each try.
Those tests show how well you're doing at breathing air in and out. They can show neuromuscular fatigability.
If you have trouble breathing in or out, are generally weak, or can't swallow, then dial 911. It doesn't matter if you don't have a diagnosis yet.
A pull monologist can also check your O2 while sitting and then while walking around. At least the good ones do that! If you aren't doing well at breathing, they can also run an arterial blood gas (ABG) to see if there are any chemical changes (i.e., high carbon dioxide) going on in your body.
What your PCP can do is to check for basic things like a B12 or D deficiency, which are very common. They might not be causing the main symptoms, but they could contribute to them if you're deficient.
In case you do have MG, try not to overdo things. Extremes of heat and cold can make MG worse. A lack of sleep and so many other things that put stress on the immune system can, too.
Tilt your chin downwards if you have trouble swallowing. Also, you could try to sip some cool water between bites to see if that helps. Or eat softer food, etc.
Take some photographs of your face in the morning (if you're better then) and when you are worse. Try to do them in the same location, same head tilt and lighting. It's best not to use a flash. It's anecdotal evidence, but healthy people don't have their entire faces droop!!
As far as sleeping goes, try to sleep on your sides. Also propping yourself up with a couple of pillows under your head and one behind your back might help. Also, speak to the pulmonologist about an overnight oximetry and/or a sleep study to assess you for apnea.
What else can we do for you?
Sometimes it takes a few doctors to figure this all out. Hang in there and get some more help!
Annie