I have never played a lot of sports or had any sports-related injuries. However, I just started taking tennis lessons and twice, since I started, my shoulder has popped out of the socket while reaching back to serve. The last time it happened was 2 weeks ago and it is still not feeling quite right. My instructor said it's not normal for this to happen without having had an injury in the past. What is the deal? Is there something wrong with my shoulder? And, if it is still hurting a bit, does this mean there is an injury and, if so, what kind of injury? Should I get back out there and play or should I continue to let it rest/heal? Any answers or advice would be greatly appreciated! Thanks!

Rebecca