Hi Atlas T:
It’s very frustrating when your furries aren’t doing well. If I were in your shoes I would look into a second opinion.
Some other things I would consider are an Rx food and testing again for parasites. Some parasites are not always detected and second or third tests might be needed. I have had very good results using Rx foods for several of my pets. Most were easily transitioned back to their regular diets. A few I had to transition to different OTC foods due to on going health issues, but they healed with the help of an Rx diet.
With an Rx food you are also guaranteed no cross contamination with other ingredients due to the strict manufacturing procedures they follow when producing the food. I have had good results with Purina, Science Diet, and Royal Canin Rx foods. Good luck!!
