Maybe your veterinarian could look at the rash and give you some clue as to the cause. Rashes may occur due to allergies to food, insect bites, allergens in the air, or because of things they contact such as shampoo, sprays, or detergents on their bedding or rugs. What makes it more challenging, is that sometimes they can even become allergic to the bacteria on their skin. If the bacteria on the skin multiply quickly, the secondary bacterial infection needs to be treated.
In the meantime, until you gain an understanding as to what all is happening, you might want to give Derma-IonX a try because it has already helped many pets with a variety of conditions. It can be given orally in the food, water, or directly into the mouth. In addition, it can be applied topically to provide relief. Derma-IonX helps to cleanse and hydrate the cells and acts as a catalyst to stimulate healing. It is better to provide the body with the nutrients it needs so it can keep the body balanced, than starting with steroid treatments early on before looking at other options. You may also need to make sure the diet is wholesome and non-allergenic. Sometimes small dogs can be very picky about what they are willing to eat and can develop some problems in that area.
Please let us know how you do and if there is anything else we can help you with as you begin to learn more about the cause of the rash.