--who have chronic pain, typically neurologic pain, from B12 deficiency and/or gluten sensitivity.

B12 deficiency is one of the great masqueraders, but over time, if left untreated, it can affect every system in the body. It is fortunate that, if properly diagnosed, it is easily treatable. But recovery may well depend on the degree of damage experienced before the diagnosis and beginning of treatment.

BTW, that big toe joint problem should probably also occasion an investigation into gout.