Sorry to hear about your dog. Unfortunately when they get his age there can be a lot of causes of his symptoms. With a $400 bill I assume bloodwork was done and was normal? If that was done 3 months ago, repeating bloodwork may show some changes at this point. Changing the diet is good to try, but now after 3 months of being sick more testing needs to be done. With his signs and assuming previous bloodwork was normal, I would be worried about liver disease, kidney disease, or possibly heart disease. Other things are possible. The best money spent would be to repeat bloodwork and see where that leads. Good luck!
Blood work was not done. That was an additional 165.00 and was offered only after the bill had already reached 400.00. He is not constantly sick but is becoming more regular with same symptoms each time. frequancy is abou every two weeks now