Too small saddle / lesson horses
So I am looking for input on a problem I am having. I recently got back into riding after a few years hiatus, but I've ridden about 20 years overall. Since I sold my horse + tack a few years ago, I am now taking lessons at a barn where riders rarely ride the same horse week to week. My problem is this: all of the saddles the barn has are very small, for child riders or smaaall adults. I am 5'8" and am by no means child sized! :) I have been experiencing a lot of discomfort from riding that I am not sure is just from unused riding muscles getting a butt kicking. I can feel myself adjusting my seat in contorted ways due to the way too small saddles. Normally, I would never think about buying a saddle unless I was buying it to fit MY horse, but I'm worried that the saddles I'm using are going to cause me to develop bad posture and pain. (like this searing pain through my outer ankles...) In a perfect world, the barn would have specific saddles to each horse, but they don't, so I'm wondering if I should go ahead and get my own saddle. Has anyone been in this situation or have any tips? I don't want to cause back issues for the horses I'm riding by putting an ill fitting saddle on them, but I also don't want to cause myself issues from the too small saddles!