It is important that the colloidal silver stay in contact with the affected area for a length of time. Colloidal silver definitely could not hurt and can only help. You can find additional detailed information about colloidal silver here . Since your little one also has allergies, you should know colloidal silver is thought to also help the immune system, giving orally might be beneficial also. For all allergies it is always helpful, though not often possible, to determine the cause of the allergy.
Some vets treat allergies with prednisone and other cortisones.
The good thing about steroids is that they are anti-inflammatories, so they reduce swelling and inflammation. The bad thing is that they are immune suppressers. Haven't heard alot, just that more vets are using it, I think trying to get away from steroids. It sounds alot safer. In general the idea is to help the animal help itself, so we want to help the immune system.