Help! My cat is pulling out his fur!

My one year old neutered male has just started pulling out his fur in big clumps. "A.J." is one of three indoor cats, and has been with us for about 6 months. Up until now he has not had any behavior problems, and none of our other cats has ever done this. I plan to get him to the vet ASAP, but would appreciate any suggestions, etc. Thanks.

Pulling out the hair could be a response to pain, a reaction to parasites, or an allergy or skin condition. Best to get the cat to the vet to be checked out-