How Can Autism In A Child Be Diagnosed?

Hi am just doing some research. My son is 5, almost 6 and in kindergarder. I just had a parent/teacher meeting and Mr. Bansy said my child may need to be tested for autism. My son is having auditory sensory sensitivity, he walks on his toes, and he has problems with transitions. This has been going on as long as he has had the capability to do these behaviors. This is all paired with hyperactivity. He just has a lot of energy. My son is very intelligent. He is top in his class. His teacher says his handwriting is the best in the whole class, his math skills are also the best in the class. He is learning Spanish, script writing, art, bible, and social skills. I do not spank him here at the house, we use 1,2,3 time out method of discipline and he responds very well to that. He is a great kid and does very well in school for the teachers, but there are those times when he can not be consoled. He was taken out of the lunch room a few weeks back, because he was asked to stop banging his lunch box on the table and to stop play kicking with an other student. So there are those times. It would happen often when he was younger, but I use a few tools, like telling him what to expect in the day so he isn t surprised. I know this is winded and I understand you are not able to diagnose over the computer, but I don t think it s autism or ADD or ADHD. I just want you opinion so I can maybe get him tested.