An uncomfortable saddle will often result in the horse reacting with the following behaviours:
- Being girthy
- Trying to nip at his side
- Reluctance to move forward while riding
- Bucking and rearing
- Rushing rather than being balanced and collected
If your horse is showing any of these behaviours, I'd advise that you pay for an experienced saddle fitter to have a look at your saddle and correctly fit it.
Sometimes it isn't the saddle - it could be that your horse has a stiff back and is tense, therefore it would be useful to loosen him up on the lunge or call a horse physiotherapist.
Hope this helps!