Although I do believe meds helps a lot of people, I also believe that diet plays an important role. I am extra sensitive to diet sodas and anything with aspertame in it. They really throw me through the roof in anxiety and difficulty with attention. A lot of children who are ADHD also seem to be extra sensitive to certain foods. I would try to avoid processed foods. Very very hard in this day and age.
I have heard that Focus works alright for certain individuals but haven't seen any studies.
Another thing that has worked for certain individuals is biofeedback. You may have to find a licensed therapist who provides that. I don't know if your son is too young for that.
Daily exercise helps.
I do believe in meds but I also believe that everything should be tried before meds - everything. In your son's situation, I think you are doing the right thing in trying other things before meds.