This may seem really out there to you, but i know that worms cause cysts in the brain and all throughout the body.
Many of us are struggling with these worms. AMA doesn't recognize most of these worms in people and don't treat us, but we have the pics and symptoms and are getting better using medicine.
Just a thought. I know people with worms and lyme disease can end up with your sisters symptoms....weakness, brain problems, paralysis, etc.
I wouldn't trust any doc to really know what is going on.