med's go on Instagram: "This presentation is classic for multiple myeloma, a plasma cell malignancy characterized by bone pain (from lytic lesions) and recurrent infections due to impaired normal immunoglobulin production. Malignant plasma cells produce excessive monoclonal immunoglobulin light chains, which are small enough to be filtered by the kidneys and appear in the urine as Bence Jones proteins. These light chains can cause renal damage (myeloma kidney). In contrast, ESR is typically elev