Suggest Treatment For Fever, Chills And Headache

maybe you can give me some thoughts. I am trying everything at this point. 3 years ago my husband developed a fever of 103 chills headache beyond belief. This was post surgical joint replacement. (to date he has had both hips, both knees, one shoulder both wrists joints replaced). He then got a skin infection starting in the middle over his lower back and running down left buttocks. This infection never blistered, never opened in anyway. He was hospitalized for 4 days on IV antibiotics. it went away. Since January of 2014 this skin infection and the headache and the chills come back every three months like clock work and every three months he is put on Bactrim. He has seen two infectious disease doctors, numerous other doctors, er doctors, family doctor and just recently a dermotologist. Other than this problem and his very severe ostioarthritis (which started in his early 30s), he is in fairly good health. Every test has been tried by these doctors however, he saw a rehmatologist 20 years ago and nothing was found. Trying to see if this could be a blood disorder or a autoimmune disease. I m always looking for help. Thoughts would be great not sure where we go from here tired of this happening to him every three months.