I have a 6 year old cat, half Siamese (Rosie). Sometimes the fur on her back will start twitching and her tail goes crazy. I just recently noticed that she's lost all the fur at the tip of her tail, about an inch worth. I was wondering if anyone has experienced this with any of their cats? What could it be? She seems to be healthy otherwise and is a pretty happy cat. If anyone knows what could be causing this, please let me know. Thanks!