My dog is allergic/sensitive to lots of things we have just discovered including environmental things like some trees and grasses and mites. On the food side he has come out as being very high positive to potato, rice and corn along with Soya bean  and wheat but are sweet potatoes like normal potatoes? It's finding nice treats for him without rice or potato but many have sweet potato.

I know I'm never going to stop the itching without medication but if I can help just a little by making sure nothing in his food is going to keep adding to his issues then that has to be a good thing.

He was on raw but then I went to just  kibble fish and potato thinking that would be good for 8 weeks but after no difference I went back to raw. He had his bloods done so whilst waiting for results I put him on the hills z/d diet until I knew what meat to exclude. Seems he's ok with any meat and fish so now I can go back to giving a raw diet, I've also started probiotics and he's been on yumove itchy dog for about 8 weeks.

Potato and sweet potato are from completely different plant family groups so shouldn't be a problem. Sweet potato is nutritionally better than potato too. I just stab them a few times and microwave then scoop out the cooked flesh. same method for us and dog no loss of nutrients by boiling in water that way and no washing up

If you're struggling with treats, make your own - you can substitute ingredients if need be or just do small chopped cooked bits of whatever raw meats he can have.  Mine get chopped duck gizzards - they are the perfect treat!  Great texture, don't crumble, easy to cook (chuck in bowl of water, microwave for 30 minutes/40 if frozen) and only one ingredient.  Absolute godsend for my dog who's allergic to a lot of proteins.