Have you tried the Furminator? I have one and I and my dogs love it! Aiden is my shedder. He is a hyper and can be nervous little dog. Stress plays a huge roll is shedding. I have a friend who swears buy the Comfort Zone plug ins. She has cats so she uses the Feliway ones.
You also might be bathing him too much. His skin might be to dry. I'd try backing off his bathing if you can. Brush him twice a day or a real good once a day to get the oils in his coat to come out.
As far a diet goes, barring feeding him the super low end foods, any good quility food can help with his coat. I myself like Natural Balance.
Also, weather has a huge roll to play. I've noticed for my dogs in the area that we live in, my two heavy shedding seasons are spring and fall. Summer is not to bad but winter they just kinda keep going. IMO, it's because I heat the house. To the dogs, it's like summer, then in the summer, because I keep the house cool, to them it's like winter. It reminds me of house plants. Their summer in our winter and visa versa.
Im not sure if this helps, but he may just be a dog that shows emotional upset by shedding. While he may stay even in attitude and manner, dealing with the stress of certain situtations -instead if an outlet like barking, jumping, being destructive and things like that- is comming out in shedding.
