What can I do to ease my dogs suffering from an allergic reaction?

I have a 6 yr old chihuahua whom i rescued from an abusive home. At his first vet visit, they told me that he needed a dental procedure and several shots. he had an allergic reaction to one of the shots thats caused him to be lethargic, depressed, and loose his appetite. the vets diagnosed him and can only suggest a 150 dollar iv treatment.any body know of supportive care i can give at home? Im strapped for cash and i want to help my pet
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Reaction to chemicals, food, fleas etc knock out a dogs immune system, so you need to build your dogs immune system so it fully functions and he can fight whatever is causing the reaction......... daily neem oil is very good which builds the immune system, promotes strong teeth and bones coat and skin and protects against mites, fleas, worms and ticks ( so you don't then need to give chemical products for protection for these)
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