Hip Clicking/Bad behavior

Question
I have a 5 year old Thoroughbred that I've started eventing. He was on the track as a 2 yr old, but otherwise has been with me. He is usually a very low key almost "hunter" personality. We have an event coming up the middle of May and the last two weeks every time i've gotten on him we spend the whole session rearing, bucking, running out, and basically balling up with anger. I'm staying out of his face and trying to get him to move forward. He's happier if he can jump. He doesn't do this when I free lunge him. But I have noticed that there's a clicking noise coming from his hip (only when i'm on him and it sounds like it's about 1.5 ft behind the saddle). I'm not sure if this is causing it, or if you have any other suggestions to get him focused. I don't want our first event with him to be a bad experience!
Thanks.

Answer
You already have the right idea by zeroing in on an unusual sound coming from the hindquarters. We all know the hindquarters can produce some strange noises but I am suspicious of it being a "clicking" noise. The most efficient way to eliminate any physical reason for this "behavioral" issue is to get with 2 professionals and work together to find the answer, your Vet and your Farrier.
Have your Vet examine your horse at liberty and under saddle if at all possible.
Explain the change in behavior and the noise and see if perhaps they aren't related somehow. If you can, do some detective work on the reason why your horse was pulled from the track. Typically there will be record of some sort of injury or incident that ended his race potential. This information will help both you and your Vet decide on the most appropriate course of treatment or change of career if needed.
All the symptoms you've described sound very much like a pain response to any sort of collection of the hindquarters. Your Farrier can determine is the reason for the clicking might not be something called "Interfering", your horse may be clicking the toe of his hind foot against the heel of a front foot while he moves. This is a common and normally easily solved problem with some corrective shoeing, but it really does not explain the acting up behavior to my satisfaction.
So first ... have your Vet take a look at your horse then contact the Farrier and have him give his opinion of your horses movement. If everything checks out fine physically, then it's going to be behavioral .,.. you may need to scale back your training on this young of a horse, take it slower to keep him from deciding to quit on you completely.

Good luck,

Stallynrydr