Kimmy, I'm so sorry you are doing worse! It must be especially hard since you were doing so well.
I think seeing your primary doctor is a great idea. She can make sure there aren't other things, possibly a new condition, making your MG worse.
Don't assume the nausea is from stress. Have you been having digestive problems?
That dose of Mestinon might be too much if you haven't been on it for awhile. That could be causing a bit of nausea too. How do you feel when 90 mg. wears off?
Since the weakness is coming on so strong and fast, you should contact your neuro right away. If you get much worse, just go to the ER.
I hope this is just a temporary hiccup. Try not to be too stressed out.
And, yeah, I for one totally get the feeling sorry for yourself thing. MG is a really hard disease sometimes. It can take away a lot from a person. It's okay to feel bad about feeling bad!
Take it easy, okay? And do something nice for yourself that'll get your mind off of it and reduce the stress.

Annie