Hi there,
now that you have done this a couple times your ligaments are stretched out and this will make your knee more likely to do this again and again. Because of the patella sliding out and over the end of the femur it runs the risk of chipping off a piece of bone. This "loose body" will need to be removed arthroscopically because it will cause you pain, locking and maybe more damage.....as you can see I definitely think you need to see a OS to rule out damage and address why this is happening. Good luck, don't wait, this is not something you want to mess with.