You need asystematic approach to discovering his allergies. He is likely allergic to more than one thing, and it isn’t just meats that you have to figure out. Plant matter has protein in it too and can cause these reactions. I understand that you don’t want to do a raw diet, but you need to do an elimination diet at least temporarily. You need to give him one protein and one starch for a few weeks, nothing else, and see if that takes care of the itching. If not, you need to try a different protein and a different starch for a few weeks and see if that stops the itching. Once you find something that he doesn’t react to, you can start adding back one ingredient at a time to his diet every couple weeks to see if he starts reacting. Then you will be able to figure out what specifically to avoid.
Some people get lucky and can find a Limited Ingredient Diet that works to start this process with, and if you want to try that route, your best bet is to try different varieties of Natural Balance or maybe Nature’s Variety Instinct LID Rabbit. You need to keep ingredient lists of foods you have tried that didn’t work and try to figure out what they have in common. If you find a food that works, you need to compare its ingredient list to figure out what it doesn’t have in it.
It’s quite a bit of detective work, but once you know what to avoid it is easier.
