Flakey skin, pulling out fur

Question
My cat is about 7 yrs. old. He has been pulling out clumps of fur on his lower back, tail and stomach area. There are not red sores, just hair thinning and loss.
    I took him to the vet but they do not know whats wrong. they suggested it was either fleas or an allergy. He does not have fleas. And there are no changes in diet or air that could cause allergies.
I have read that this may be caused by stess. But my cat does not exibit any behavior that would suggest he is stressed. He does not appear to be in pain, he is at a healthy weight. He also has recently shown signs of increased dandruff, but then again, it is winter over here in WA. I don't know if you have any idea or not but thank you for your time in reading this.

Answer
Hi Hillary,

Since you've been to the vet I assume they ruled out ringworm (a fungus) or mites. Some cats do have an allergy to fleas but more likely he's developed an allergy to fish which is very common in cats.  Since most cat foods have some amount of fish in them you'll have to start reading labels.  I believe "Good Life" dry food doesn't have fish and many of the Friskies Special Diet canned foods don't.  You might try that and see if it helps.  Did the vet give you any medication, such as steroids? That's the most common way of treating skin disorders.  You might also try a medicated shampoo (check your pet store or on line-try ryanspet.com) to help with any itching he might have from the dry air.