Welcome!
I agree with Portia in starting with the question, "Is my child happy?"
That said, there is a lot of information which may be considered "Gifted 101" or a great starting point in learning about giftedness, which may help you support and understand your child.
If you are looking for IQ testing, there is info on
Hoagies Gifted Education Page, including inventory of tests, lists of Psychologists and test administrators.
If you are looking for information on possible ADHD because he couldn't stay seated practicing piano, then the website of
Understood.org and
wrightslaw and/or
2e newsletter may be of interest, along with this
SENG youtube video on Misdiagnosis and Dual Diagnoses.
If you are looking for math resources to use at home,
Beast Academy may be of interest.