eat liver

vitamin A probably. it's an anti inflammatory vitamin, and liver has the good kind your body can process well and a bunch of other useful things.

allergies are cured by exposure to the allergen but your body doesn't have high inflammation

vitamin a will reduce inflammation
vitamin d also reduces inflammation (sunlight)
selenium helps your immune system recycle it's immune cells faster, and liver has a lot of that as well (among b vitamins and even some antioxidants, proteins you might be lacking)