What I do is I lunge him, and when I ask him to do anything more than walk, like trot for example, he'll trot a few steps and then his ears will pin and his tail will start flicking. Cantering is worse. He'll be reluctant at first and then he'll buck and reverse away from me as if I'm about to beat him, and sometimes rear before falling into a canter. As far as I know, he's NEVER been whipped, abused or hit associating with a saddle or lunge line, and does beautifully without a saddle on and with a bareback saddle pad on, and I know its not the lunge line because I've done it in a round pen too with the same results.
After that first time he doesn't throw any more fits about it but he does whirl his tail and pin his ears periodically. It's not like he's never had a saddle on before, he's broke to ride and all that, he's 7 years old. I've had him about a month or two and he's been like this for as long as I've had him.
Is there something I'm missing here? I'm totally stumped. If my little guy's in pain, I don't want to make him endure anymore of it. All opinions and suggestions are welcome.