Last month my husband recovered from viral fever after one week of the viral he is suffering from ankle foot knee waist mid back and neck shoulder pain , his HLAB27 is negative and MRI OF SI JOINTS is quite normal , ESR 16
CRP .68 , and all test for arthritis is normal , pls guide what could be the reason, presently he is taking ETOVA MR 400 MG , still complaining the pain and stiffness