Hi. My 9-year-old Nephew Has Been Having A Lot If

Hi. My 9-year-old nephew has been having a lot if fatigue and brief periods where he turns ashen gray, complains of a "fuzzy head" feeling, and has pain on one side under his ribs. All bloodwork is ok (iron, liver, kidney, sugar, CBC, etc. except rge marker for past Epstein Barr. I saw him again today during one of these episodes and he looks like a very sick little boy-gaunt looking, though no weight loss. Can you offer any suggestions of ideas as to what else his ped should bd looking at? Sure would appreciate it. Thank you much!
Kristina Corbett