The thread you are answering to has been dormant for 3 1/2 years. If you have questions, please feel free to start a new thread. Welcome and hope you post again.
It sounds to me that your kitty could have inflammed bowel decease (IBD). My cat has IBD. And some of my prior cats have had IBD. The symptoms are usually vomiting or diarrhea and weight loss. If I am correct your Kitty needs medicine to control the decease and special grain free hypoallergenic food. Rabbit, Duck and Pea, or Venison is the recommended food. I learned that an ultrasound will identify IBD, blood test usually will not. EVO will not help. I tried it. Luckily I only gave my cat very little. Even with his medicine he got sick.
I recommend that you discuss IBD with your Vet asap. The good news is that IBD can be controlled and your kitty will feel match better.