My husband started feeling bad last Tuesday evening. He ran a low-grade fever and felt achy. He thought he might have the flu, but by morning felt fine. All day Wednesday, he felt normal -- no fever, but a little tired. On Thursday, the low-grade fever and achy muscles returned. Friday - no fever so he worked at our farm - some of the work was heavy. Throughout the weekend, he felt overly tired and ached again. Today, his arms, elbows, and fingers are hurting to the point that it s hard to move them. He is again overly tired. No fever. Please advise.