Trust your instincts. If something is telling you that he’s not like “typical” 4.5 year olds, follow that voice. Have you talked to his pediatrician about your concerns? If the pediatrician isn’t giving you what you need, then go to the next step and talk to a psychologist who’s well-versed in ADHD and associated conditions. Have you checked out the links on this site? Look under “Symptom Tests & Info” there are self checkers such as https://www.additudemag.com/category/understand-conditions/symptom-tests/ and others… use the resources here.
The best piece of advice I could give you is to not lose any more time. I suspected something was up with my son when he was little and was always told that I was looking for issues that weren’t there. Fast forward a few years later and my son has been diagnosed with a few co-existing conditions. You know your child the best, so listen to that voice that’s telling you something’s up.
The good news is that if there is something going on, you’re finding out early and early intervention is great.
Keep us posted!