ADHD diagnosis?

I think my 11 year old has a form of ADHD. I never wanted to label my child but his school work is really started to be affected. How was your child diagnosed with ADHD? And who diagnosed them? I live in Michigan If that makes a difference. My husband sees a psychologist for work and he offered to see my son. I’m not sure if he’s the right person and I heard psychologists can’t prescribe medications anyway. Any advice would be great.