Was somebody shooting at your car? Well if there is an exit hole there has to be an entry hole. Did you find that. I almost have not idea of what part of the car is that. Can you post a bigger picture for context?

The rear shocks are held on the inside of the rear wheel well. Not accessed by the inside of the car. If you can't find a welder you can grind it flat, sand it and bondo that repair just to keep things from rusting.