So do I ask his pediatrician for the test or go to an optometrist?
I would just call an optometrist, but to be honest with you I am not the type to rely on my pediatrician much. Now I'm sure your pediatrician would gladly refer you to an optometrist, if that makes you feel better.
My kids haven't had their eyes checked yet, but it would probably be a good idea. I needed glasses as an older child and didn't realize it until they checked my eyes and told me I did. Once I had glasses it was a work of difference!