Hope your daughter can remain pain free.Yeah, my daughter got a small injury to her SI Joint (in the back). Comes from not being symmetrical in use and development. I'm a little surprised more softballers don't have/get it. PT and stretches seem to have relieved it. The off-season came just in time.
In the last year I have heard about 3 different girls in a 1 hour radius that have had broken backs that were all pitchers. I do not know all the details of the injury. Not sure if it is some kind of fracture in the back. Sorry for such a vague description, wish i knew more details.