Child with recurrent rib pain and fever

My son, age 9, has had recurrent bouts of pain in his ribs. Each episode consists of a sharp pain in the same spot on his ribs, dark eyes, fatigue, and a fever of around 101 degrees. Each episode lasts for 2-4 days. He has had seven episodes: 05/2011, 12/2011, 05/2012, 08/2012, 09/2012, 10/2012, 11/2012. During an episode it hurts to laugh or breathe deeply. The episodes are becoming more frequent, and this last episode has continued for longer than normal.

During the first episode, the pain was so bad he could not walk. They suspected appendicitis, but an ultrasound turned up nothing and surgeon determined it was not appendicitis.  During each episode, the inflammation markers in his blood rise (ESR 20, CRP 67), but then fall to normal levels after the episode ends. An X-ray showed nothing. A CT scan during an episode showed no problems with the digestive system or any signs of cancer, but did show a pleural effusion in the exact spot where he has the pain. The pulmonologist found no trouble with his breathing when he was tested between episodes. He tested negative for TB. He does not have significant markers for Lupus.  He has no cough, nausea, or vomiting, and he only occasionally has diarrhea.  

Does anyone have any ideas about what this could be?

[AnnieBrooke]

Has he had an MRI of his chest?  It almost sounds like there is either something like pleurisy or some kind of vascular issue (like an aneurism (aneurysm)) in his chest, though I have NO idea whether that is even possible.  I'd push for the MRI and then for a referral to any other specialist who might be helpful in diagnosing the issue.

[margypops]

possible gall bladder pain, pin of gall bladder is severe, and starts under the right ribs, radiates up and very often into the back, check if its worse after eating..

[jmugan]

Thanks for the ideas. We will check into the gall bladder and the vascular possibilities.