2 female cats roughly 12 and 13 yrs old. So being low income I've always had to get cheap food and my cats have never had issues with it. I was typically giving them Purina Cat Chow for years and then opted to try a slightly better food that didn't have all the coloring and went with the Purina Naturals which gave them no issues. I've always for years noticed the occasional every other day food vomit from one or both my cats, but it seemed to increase slightly after a year or so on the Naturals... so then I came across Purina One Tender Selects and started them on that in June of 2017. Everything seemed fine and then we had an issue with Fleas around June of 2018 and took me months of treating the carpet with flea insecticide and keeping both cats on Advantage Plus which I continue to put on them every month since then. Since the flea problem I at some point noticed my youngest cat was licking at her chest, legs and feet... as well was always scratching at her head, neck and ears. I of course kept thinking it was fleas still but would constantly check and haven't found a single flea in 8 months. Now a couple months ago I noticed while rubbing her belly that she had a sore on the left side of her chest where she does this obsessive licking. Took her to the vet and this new vet was rude... didn't say much, grunted through the entire appointment and wouldn't answer any questions. He put her on a steroid and said it should clear up within a couple of weeks, but it didn't. I started Googling the issues and it seemed like the biggest culprit may be a food allergy with the scratching around the head and neck area... the dirty left ear, the licking and the vomiting of food. Talking with a friend we tried switching their food to Hills Science Diet for sensitive stomachs and skin. For 2 weeks straight there was not a single food vomit from either cat. But then I noticed scooping my youngest cats litter (youngest uses normal litter box and oldest uses an older model electric litter box.) that there was no bowel movements, checked the next day and the smallest of movements and then checked again the following day and nothing. Took notice to the food bowl and that it hadn't gone down very much. Apparently at some point my youngest stopped eating the Hills food and for who knows how many days was only getting the little bit of wet food I give late at night for 4 nights as a treat. Thankfully I still had some of the Tender Selects so pulled that out and filled a bowl and she's back to eating and normal bowel movements. But of course she is still doing the scratching and licking which the sore isn't any better or worse and have to keep correcting her when she licks at it. Not sure what to do. I read it takes up to 12 weeks for them to detox a food they may be allergic too, out of their systems. But I'm not even 100% sure it is a food allergy. It could be a nervous issue since the fleas... could be the flea meds... could be the dry food or could be the wet food. My options are limited with being low income and just don't know where to start. The Hills was expensive and were only on it for a couple weeks so that was a big waste of money I didn't have to begin with.