I/we (volunteers who handle used books, including vintage books) are suffering upper arm pain in both arms. Lifting, injury, etc., ruled out. Inflammation caused by mold on books? Allergic reaction to dust/mold? Except for runny noses and some eye irritation, no severe respiratory symptoms. Blood tests (general) are normal. Pain is constant. I put my pain down to age and possible injury (massive lifting), until another senior, who is otherwise in great health, began complain about same symptoms. Immune system response?