We just moved back in with my father in law due to the loss of my mother in law. Our 10 year old lived there before so she really only seemed a little stressed for about 2 days, then was acting normal again. There are two other cats but they don't fight or anything. All indoor babies. About 2 weeks ago we wanted to try a different food since she is a senior now and we realize that she needs different nutrients than the 2 younger ones. We bought a good quality dry food as well as treat that is "raw infused" and for 4 days she loved it. We mixed the foods together to help the transition. Then all of a sudden, we saw she was not eating much, but was still drinking and acting normal. But now she is acting very lethargic, vomits a yellowy to white foam usually after using the litter box, drinks but is not eating, and is acting different. We took the newer food out completely and gave her back the old stuff thinking it was just the food. But although she eats a few nibbles here and there, it isn't much. She appears to have lost a little weight now as well. If anyone has any ideas we would appreciate any feedback. Planning on a vet visit if no changes after the weekend. Thanks!