Rachel,
Sorry that you're not feeling well.
I'm glad that your new neurologist has not given up on you (as he shouldn't) and is continuing on in other diagnostic avenues...Don't be down, although I can understand how it's easy to be down with the situation...I know that you're going to get help soon, I can feel it...It's not your fault that you're sick and someone is going to help you soon because you haven't given up on yourself...
When you described the darkening of your eyelid, it reminded me of the pic. on wikipedia of the ptosis...Check it out..
http://en.wikipedia.org/wiki/File:Myasthenia.jpg
When my tongue is really weak, and I can't barely move it, I've noticed that it's not the same colour as when I can move it...It's very strange, and I've always wondered about it...When my tongue is weak, it's really pale, colourless...When it's normal again, it's red- like it's supposed to be...It's almost as if the blood isn't flowing as well to it when it's weak...
I've always likened my persistent tongue weakness to the persistent ptosis that others describe...The intensity of the weakness is the same, just a different location...Maybe when the receptors are really 'down' this affects blood flow too in some way...
Anyway, don't give up! We've all got your back here- this neurologist will treat you as should be!
Take care, Rach
Nicky