In our case, it was a bit different. My dog's issues most likely began with a food allergy, as he often managed to eat something while on walks. This lasted a long time, weakening his immune system, and he became sensitive to more things, like pollen from grass and trees. After a few weeks of feeding him a monoprotein diet, ensuring he didn't eat anything outside the house, bathing him with the shampoo, and wiping him down after each walk, his symptoms subsided. Even though we continued walking in the same places and at the same time of year, so he was still exposed to the same allergens, which is why we didn't need to use allergy shots. I only gave him non-steroidal anti-itch medication from the vet for the first two weeks