There might be a diagnosis behind his behaviour like ADHD. I would discuss your concerns with his GP and maybe get a referral to see a pediatrician

Have you looked at his diet, I know my 5 year old is very unsettled if he has too much sugar during the day. We have cut out all packaged food and only have fruit and vegetables for him to snack on, we also do bed time story and limit tv viewing after a certain time. But I would also take him to a GP and get a professional opinion on the situation also.

It may be time to take him to a GP! Don’t feel like a bad mumma, kids are exhausting and you caring and seeking help just shows you want the absolute best for him!
There may be an underlying issue with his Melatonin levels, which is the brains way of getting us tired and ready to settle. Your sons levels may be lacking which means it won’t be giving him that feeling. A GP can request bloods to look into this for you