If his primary problem is an attention deficit disorder, the most effective treatment is generally appropriate medication. It is critical, however, that if you do decide to go the medication route, that someone reviews his response to medication on a regular basis (monthly, at least at the beginning). Your family pediatrician is usually not the best person to do this. You need to consult with someone who has comprehensive knowledge of the range of medications that are available today -- someone who can help you to weigh the pluses and minuses of each possibility for treatment. A consult with a pediatric psychiatrist or psychopharmacologist can be helpful. Your local hospital may also be helpful in helping you to find a good referral.
Behavior therapy can also be a useful part of treatment. You might also want to read Betty Osman's book, Learning Disabilities and ADHD: A Family Guide to Living and Learning Together. I know this is a difficult road for you, but I hope you can take comfort that you are on the right track. Good luck!