I took my son this week as a matter of fact for a full realm of testing. Try Jewish Family Services. You don't have to be of the Jewish faith to go to them. They have a great team of Psychologist, counselors, etc. and will do a full scale testing on your child for ADD/ADHD, mood disorders (which often accompany ADHD), and several other issues. We spent the better part of 3 1/2 hours with them. First we answered questions and then they took my son in for two hours of combined copmuter and paper tesing. They also sent home a set of questions that we are having his case manager at school fill out and we will fill out a pack at home. Once these are completed and returned they will score all test together and give you the best diagnosis and plan for your child.
By the way, my pediatrician diagnosed my son without testing years ago and I thought I would never get the school to help. The school can only test for educational needs. So finding out the right information has really helped us. If you need any further information, you should contact your local county/city mental health office.
Good Luck....you'll be glad you got the help.