She might be stressed, and picking out her hair out of nervousness, but it might also be the food. Look up the recent issues related to grain-free and also google issues related to the brand of food. Just because a food is cleverly advertised and costs a lot does not mean it's perfect. (Also, grain-free foods often use potato instead, not that good for cats.) The cats-only vet in our area says to give canned food only. You might try that, or at least give her a combination of canned and dry, and see if anything changes.
Also, your flea treatment -- once a month is pretty often. Is it a product prescribed by your vet, or something over-the-counter? In our neck of the woods, people see these OTC products at the feed store and assume they are safe because they are sold to the public, but some are very harmful to cats.