I have a cat that I took in after my neighbors moved away and left her. She refuses to be an indoor only cat. I recently bought a bag of purina one hairball formula and after eating for a day, both my cats started vomiting at least once a day. Felix, the cat in question, developed scabs on her ears and head. Since she is an outside cat but comes in to eat, I thought it could be a combination of allergies to food (since my other cat also has been getting sick) and environmental issues outside. I mixed in taste of the wild food a few days ago but when I noticed her scabs last night, I dumped all the food and bought a new bag of taste of the wild. Also bought a new flea med, advantage. Any ideas? If it doesn't subside in a few days after feeding only the new food, I'm taking her to my vet.