Swelling and pain on left side right at bottom of rib cage....?

This is a touchy subject for my husband and I. Dr.s aren't giving us all the answers we feel we need. About 2 months ago my husband became deathly ill, he contracted a horrible MRSA infection which led to sepsis and pneumonia. He was in the hospital for 2 weeks and had to have surgery and chest tubes to drain 4 liters of fluid from his chest. He just ended 6 weeks of IV antibiotics for this particular illness. Every Dr. he sees says it's a miracle he survived. It's all thanks to the good Lord's love and grace. However...he has gone back to work (too early) and works very long shifts. He now has pain and swelling on the opposite side underneath his rib cage. He has had no fever, no other symptoms other than this pain. The ER said he was fine...blood work great and did xrays. They stated that all the muscles, nerves and bones are connected and the pain and swelling from the surgery (opposite side however) may travel and cause discomfort. His own primary Dr. says she doesn't know what it is either...she sent him for shingles testing! Which it's obviously not. I'm afraid for him...he is a strong man but something isn't right here. I don't have big faith in these Dr.s due to it was the ER that sent him home saying he had a viral infection that would pass in a week...had I listed to them, he would died in my bed! I took him into a different ER 2 days later and by that time his liver was basically failing and he was in fact dying. He has come such a long way through his healing...don't want to just let this go. Has anyone ever heard of this? It may or may not be connected to his previous issue. Would appreciate any insight as we look further for answers in a 3rd, or possible 4th opinion!