Re: nerve pain
Her shoulder problems might have led to early osteoarthritis, which in turn is leading to even further nerve damage.
The symptoms of the last year, (swelling, numbness, pain, hair loss, brain fog) may or may not be unrelated to the nerve damage/osteo.
The symptoms you describe could be from any number of different disorders. Maybe endocrine, like hypothyroid? Or autoimmune. Do any autoimmune disorders run in your family? (rheumatoid arthritis, lupus, celiac, etc)