What Causes Chronic Body Pain With Muscle Weakness?

My husband is been in chronic pain 5 yrs now. 1st diagnosis polymyosis, then PMR, then ALS, fibermyalgia , Lyme disease, chronic pain & drug induced myosis from prednisone.then none of the above only results low cooper & low b12 which he is on medicine for. He is getting worse everyday. Chronic full body pain 24/7 muscle weakness & shin pain ( has had muscle & nerve biopsy) which where fine