I am so sorry to hear that!
I haven't read that there's a connection between Mestinon and kidney disease.
Have you been evaluated for lupus?
Did the nephrologist give you a plan? A different diet? A placement on a kidney transplant list or a plan for doing dialysis?
My Dad had kidney failure and it's not a fun thing to have happen. If you are going to up for a kidney transplant, make sure you ask if it's a good kidney before you have a transplant! Some of the ones they transplant aren't.
Did the nephrologist say if any damage could be reversed? The body has amazing healing powers.
NSAIDs are wicked bad for the kidneys when used on a long-term basis. I'm truly sorry you're having to go through this. I hope you'll speak to both your neuro and primary doctor, too.

Annie