Stacy, that happened to my Specks a couple of years ago (she's a 100% indoor kitty) and it turned out to be an allergy to flees. I must have brought them into the house. A dose of Advantage and they were gone and the fur all grew back.
You may want to get yourself a flea comb and comb down by the base of the tail. If you see any tiny black specs, that could be "flee dirt" or "flee poo." Have a glass of water handy and if you see any flees, then drown them. It's really the only way of killing them.
Good luck, and keep us posted.
Life should NOT be a journey to the grave with the intention of arriving safely in an attractive and well preserved body, but rather to skid in sideways, champagne in one hand and strawberries in the other, body thoroughly used up, totally worn out, and screaming WOO HOO - What a Ride!
Sometimes the most real things in the world are the things we can't see
Until one has loved an animal, part of their soul remains unawakened.