Some children do require a little help with medications, and it sounds like your child is one of them. God bless you! I remember what it was like.
There are certain medications that last longer, and if the pediatric doctor is quite familiar with all the meds, the combination of meds... he or she could recommend either an extended release or longer-lasting brand, or an added small afternoon dosage, that could help. My son outgrew the ADHD. But when he was young, I feared having to try him on medications, because of their side effects. Sometimes it was worth the hassle of giving him all of my attention, than it was to give him something that would cause him to have bad dreams, or such.
Watching his diet and eliminating possible food allergies (reactions?) is an excellent idea. It is going to take a combined effort by parents, grandparents, baby sitters, and everybody, to find the right combination of things that work for him. And you will, eventually. My son's condition was so serious at one point, that his father used to have to tie him to his chair to the dinner table in the evenings when he was three years old, just so he could stop long enough to eat. He also had a bedwetting problem, and I had to cut off any liquids but sips of something after 6:00 p.m. If you decide to try "natural" substances, at herb stores, perhaps get in touch with a holistic doctor first, as some things could make it worse. I pray you are able to find the help you need, and yes, there are all kinds of support groups available for moms like you. It will take much effort on your part, to find the right combination of activities, the right elimination of foodstuff, etc., for you to get this happy medium.
May God bless you richly with good advice in this endeavor.