English differs from Western in that there is no horn on the saddle (the hooky knob thing in the crotch area). If you ride for long, especially English, look into getting a custom saddle done. They measure your horse, and more importantly your rear! your crotch will thank you too
Also, are you posting your trots? if you sit when the horse is trotting that can rub you the wrong way too. just remember - Heels down and your posture will fall the way it should
