The thing with commercial foods is that they contain grain which are a huge source of Omega 6. Even meats these days are grain fed (if you're lucky) instead of free range, like they are meant to be. This is why Omega 3 supplementation becomes important.

What dosage of fish oil are you using? The standard dosage is 1000 mg per 30 lbs of dog's weight, but for health problems (such as arthritis or allergies) you can go up to 1000 mg per 10 lbs of body weight. Typical capsules that you buy at the pharmacy are 1000 mg each, so that makes dosage much easier.

Personally, I use the capsules instead of the liquid because it's so much easier. I am able to buy them at any pharmacy which is less expensive, currently we're using the Costco ones. Also, much less messy and my dogs eat them like they are treats, although the first time I had to poke the gelcap with a pin and squeeze some out to show them that there was good stuff inside. My dogs eat a raw diet, so I give these to them after their meal - they consider it dessert. If you feed a kibble you can just toss the capsules in the bowl.

Do you know what she is allergic to? If it's a food allergy then just switching to the right food may help with the itchiness. Not too much you can do if it's environmental, and I'm guessing you have already eliminated cleaners and pesticides from around the house? One of my dogs gets very itchy in late fall, once winter gets here she is back to normal - but there isn't much we can do to avoid the cause of the problem.

The proper amount of OFAs depends on the health of your dog. Some dogs have problems such as skin issues, certain heart diseases, or arthritis, all of which can benefit from additional omega 3 fatty acids. Omega 3 fatty acids also help cognitive function.

Omega 6 fatty acids are good for other things such as diabetes, osteoporosis, cancer, high blood pressure, other types of heart disease.

Foods such as salmon and tuna have naturally higher levels of omega 3 fatty acids which may be more beneficial to your dog unless she has other problems. Lamb-based diets do not have much omega3 unless it is added by the manufacturer. There is a point of diminishing returns where adding more and more OFA-3 does not help any more. If that happens, I'd have the vet figure out what is going on.