Weird Symptoms..Docs are puzzled.

Hi everyone. I posted earlier about hypokalemic periodic paralysis for my mom. A Neuromusclar Specialist in TX (Dr. Trivedi) says does not have it. Since then she has developed more symptoms.
She still "loses movement" from her neck down but it she said this time it feels like her arms and legs are just too heavy to lift. She is completely exhausted and the littlest things wears her out (shower, bathroom)
Some days she can walk with a cane, some days she has to use a Walker or a wheelchair. It seems like every day is different. She also has high blood pressure spikes ranging from (180-200/100-110) and heart rate spikes (100-125 bpm.) Shes had multiple tests done, MRIs, (cervical,thoracic and lumbar) CT scans, blood tests, chemical stress tests, thyroid function tests, 24 hour urine tests, and just recently had an EMG and a skin Biopsy does that did say she is positive for "Small fiber polyneuropathy".
Some days she gets up to walk and can't take the first step, because her legs start to tremble, and she gets very shaky
She says it's like her feet are glued to the floor. Then once she starts going, she either walks good, or walks very slow and shuffles. Sometimes sitting up her whole body starts to shake..
But all of her tests come out normal. Does anyone else have these symptoms?
Can small fiber polyneuropathy cause all of this or do you think there is an underlying cause?
Thank you.