Cat problems

Last week I was feeling pretty grumpy because of my MS. This week I am remembering that I need to be patient to see how this new drug works.
One problem that has popped up is that the cat, Macy, doesn't seem to be eating very well. She has been losing weight for quite a while my wife noticed the other day that she hadn't eaten much food in 3 days. I'm a little worried about her. I got online and looked it up and it seems like it might be something serious. She's always preferred dry food since we got her and would not eat fish or tuna. Matt tried replacing her food with the new batch and hopefully she will eat some. The website also suggested fish oil, broth or cooked egg. Hopefully she'll snap out of this. She just went to the vet at the end of June so I don't think it's her teeth that are bothering her or they would've said something I think. I hope we can figure this out without too much trouble. She has gotten used to the dog and doesn't run away the company there are now. We don't think it's the dog being around that is bothering her. I love my kitty and I wanted to be happy.