I mean it's not something that will go away, but you should be able to keep her comfortable. You may want to consider something like devil's claw. Anti-inflammatory and pain killer (wouldn't do meds unless necessary) but again, at her age I would hope that isn't needed yet.
Even if 24/7 turnout isn't an option (ideal, but some places can't/won't do that) she should still have as much as possible. 3 hours is nothing. I hope she has a big box stall for when she is in, the more movement the better. Do what you can to encourage it.