I have a 15 year old cat. a year ago I started to change his wet food to Fancy Feast Senior. I quickly saw that he was losing weight and then started having some leg/balance issues. I immediately took him off that food and put him back on Fancy Feast. Since he also has “throw-up” issues occasionally, I also started using Wellness Core for digestive issues. He eats 1/2 can of each for breakfast and also for dinner. He likes them both and eats them well. My concern is that he still seems too thin. Is there a better choice? Should he have something with more protein?