Hello, I Have An 8-yr-old Grandson That Has Been Diagnosed

Hello, I have an 8-yr-old grandson that has been diagnosed as ADHD and I have been having a problem finding a pediatrician that knows how to deal with this disorder or specializes in it. He is in my custody at this time but he has also had some trauma. He has tenn-care insurance. Can you direct me in the right direction? He has gone to Alliance Healthcare Services on Winchester in Memphis, TN but it's not working well for him as far as improvements.