Cat losing fur in patches, and itchy

Question
My 7 yr old cat seems unusually itchy. She is losing fur in a spot behind neck, and skin seems scaly. Spot was size of nickel, then of a quarter, now it's 3" diameter. The spot first occured after an application of flea medicine on the back of her neck. I have been giving same treatment to her for years without a reaction before. She now has a spot of fur missing under her left wiskers. What could be going on is this an allergy or something else? ringworm? (possibly from new cat brought to house month ago), allergies? stress?

Answer
YOu probably should let your vet look at this cat to see if it is a toxic drug reaction from applying flea control on the skin. That happens occasionally.  But it could also be something else and without an examination, I cannot tell you what this might be.