Red Itchy Splotches?

My cat is developing red itchy splotches along his spine. They have now spread down his sides, or at least I have found a single thin furred red spot on his left side near his hip. Do these sound like potential allergies? Rash? He is on a balanced pre-made raw diet from Darwin with the main proteins being chicken and turkey. His next batch is going to be turkey and lamb though as I suspect he may be having a reaction to the chicken. He has always been sensitive to chicken back when he was on commercial kibbles, but I have heard that cats sensitive to chicken in kibble are usually fine when it is presented to them raw. Since usually the sensitivity is caused by the chicken in kibble being over processed. He has no fleas or other bugs that could be causing an issue.

Hello!   My antenna always twitch when someone says 'my cat has no fleas.'  How can one possibly know?  Many's the time I've looked for fleas on a pet to find later that they had them - fleas are just very good at hiding.  For a cat who is allergic to fleas to start scratching to this extent, they simply have to be exposed to one single flea, which might long since have jumped from the cat and thereby not be visible.  The vast majority of vets begin to treat this kind of problem by using a veterinary-grade flea treatment (there are many different kinds) as frequently as recommended for a 12 weeks while at the same time treating the symptoms.  Only if they are still scratching after that, can fleas definitely be ruled out as a cause.

Assuming however, that fleas (by far the most likely culprit for clinical signs as described) have been ruled out as a cause, there are other possibilities.  Mites, certain flies and other beasties should be considered and also, as you hinted, allergies.  I would rather my cat had fleas than an allergy, as allergies are for life and I disagree that cooking chicken or feeding raw food will prevent allergies to the other.  Vets usually rule out allergy by advocating the feeding of specifically designed feed containing a 'novel protein source', but not all allergy products are scientifically proven, so if the investigation were to get to that point, it would be best to chose one recommended by your vet and not give any other foods alongside it. Please do let us know how you get on in due course.