possible dog shoulder dislocation??

[Packman]

Our 5 yr old golden doodle has a sore leg.  It has been bothering her on and off for quite a while.  We took her to the vet and he couldn't fell anything upon examination.  She chases a ball like a banshee and seeems just fine.  Later in the day she limps around.  Took her her to a new vet and he suggested the dislocated shoulder.  Doing xrays in a couple days.  Is it really possible that she has a dislocated shoulder and yet runs like crazy to chase a ball.  We throw the ball 3 or 4 times and she has no problem.  we take it easy knowing it may bother her later but she still loves to do it.

Thanks