My son is almost 9 years old, I took him to the hospital about 3 weeks ago for his back hurting him, they did an ultrasound and found he has an enlarged spleen. The er doctor ran a blood work up, he doesn't have mono, his CBC was normal so they sent us home to follow up with primary. They did an ultrasound Wednesday and called me today to say they are referring him to a pediatric hematologist in San Francisco but won't tell me what it could be or why they can't take care of it. Have any of you had this happen? What could be wrong with my son?