I agree, I'd try the red meat version of EVO. A lot of dog foods contain lamb now and it's not as good of a source for allergies as it used to be when it was less popular.
If the red emat EVO doesn't work for you I'd look for something that is grain free and contains a less popular meat like venison, rabbit, fish, etc...
And keep him on the same food for at least 2-3 months. Also remember to pay attention to the treats that he gets. Make sure they are also free from ingredients that may cause flare ups.