Try this. If your child has behavioral problems in other settings, such as day care, schools, friends homes etc, when you are not present this is a red flag. If only with you present, it still is a problem, but less likely to be an emotional disorder.
Your pediatrician. Should have Vanderbilt or other checklists for you & the teacher to complete to screen or assess for a neurodevelopmental disorder or mental illness. After reviewing health, growth, developmental, behavioral & family history, performing physical & neurological exams & discussing your discipline practices & family stresses, (s)he then refers to an appropriate mental health provider, if necessary.
Try a good book. I can recommend a good e-book. It's called: parenting the kids according to a child psychiatrist. It's available on kindle for only $5.95, I think you will find it to be a tremendous help and good luck. Also, check out on amazon the dvd called: the 20 minute behavioral miracle.