Noomi has allergies too. She has both indoors, outdoors and food allergies. And also allergic to the fungus that you find in the dog's fur (she has only under her paws), so she is kind of allergic to herself.
It seems like indoors allergies are quite common, and that most of allergic dogs have some sort of indoors allergies. Mites that lives in dry food and in dust, sheets, coach etc. So reducing the amount of mites will be a good start.
The one that lives in the food are the easiest to reduce. Just freeze all food and treats for at least 8 hours. All kibbles contains some amount of mites, but it can be frozen. Meat doesn't contain mites, but then it's the ethical part and not all are comfortable to feed the dog meat.
The dog's bed should be of any sort of fake leather or similar fabrics. The mite doesn't like to live there, and it's easy to clean. Just wipe it with a wet cloth. All other fabrics that the dog sleeps on should be washable at 60 C / 140 F, as it will kill mites. Or be put in the freezer for at least 8 hoers. The best is to kick the dog out of the bedroom and coach. But I couldn't. Noomi still sleeps both in bed and coach. I bought some mite block sheets both for the bed and coach. And it has helped a lot.
For indoors allergies, good washing routines helps a lot. Soap doesn't kill mites, so to wash with a clean cloth and water is good enough. I bought a lot of microfiber cloths, so I only use them once and then wash them at 60 C / 140 F. My vacuum cleaner has also a HEPA filter. The best is to vacuum clean right before you leave the house for a couple of hoers (with the dog of cause.
). Keep the temperature in the house not too high, and reduce humidity (I don't know the weather at your place, so not all places are easy to control such things).
Food allergies are discussed if can be showed on a blood test or not. Some say it can, some say it can't. Noomi took a blood test that shows food allergies. I removed those ingredients from her diet, and for her it has worked. I was advised to start to give her a protein source that she never had eaten before. And then start to introduce one new protein source at a time. I haven't done the last thing, as I found a brand that doesn't contain the ingredients that the blood test claimed she was allergic to, and she has been better.
I give Noomi apple cider vinegar in her food every day, MSN powder and a omega 3 source (fish oil). The vinegar is to help that fungus and yeast doesn't grow in her fur. MSN and omega 3 should boos the immune system at bit.
One of the positive things about taking a blood test, is that it's possible to make a “vaccine” for the dog. I don't know the prices in the US for it, but here in Norway it quite expensive (price depends a bit on what the “vaccine” contains, Noomi's is one of the cheapest one, and I think it's about $450 a bit under a year). Her insurance also pay only for two treatments, and then I have to pay for the rest of them. But that is for Norway. Check up for your country.
Find also a good shampoo for your dog. The first one I got for Noomi from the vet, only made her worse and she scratched like hell. So if a shampoo doesn't help, try a new brand. Even though one brand is supposed to be the best, it's not always the best for your dog. Like ear drops. Noomi get a really bad reaction on the one that is supposed to be the best. So she needs to use an other brand. You can also mixed some vinegar with water and put in the fur at the last of showering (and don't use more water after that).
When the paws are attacked with fungus, I use paw socks at nights on Noomi. Treat her paws in the evening, put on some ointments and then she can't lick it off (she leaves her sock on always). So good socks are important here.
If the dog has outdoors allergies too, it get a bit harder sometimes. Special when all sorts of pollen are spreading. But take a wet cloth and dry of the dogs after walks. If she has taken bath in lakes with a lot of pollen on, just wash he off when she's at home. Noomi has some pollen allergies, but not of any threes that are a lot of where I live, so we're lucky there.
I like to do one thing at a time, and not all things at once. As I loose a bit track of what works then. And suddenly you are at the level that scratching etc is reducing.
I hope something can help you, and the best luck for both you and your dog.