Enterpriz

I have a 2001 Audi A8L. I hit a deer and destroyed my passenger side headlight. I replaced the headlight and everything is fine there. But shortly after the rear running lights on the passenger side stopped working. On the passenger side of the back it has 1 running tail light in the trunk, one on the quarter fender, then a blinking/brake/turnsignal light, then a marker light. So there are 4 bulbs on the passenger side rear of the car. The only bulb that's still working is turnsignal/brake light. When I turn my headlights on all 3 of the running lights on the drivers side turn on just fine but none of the passenger side ones turn on. The only bulb still working on the passenger side is the turnsignal/brake light. The 3 lights that would turn on when the car is running with the headlights on no longer turn on. It started with the bulb in the trunk it went out. I replaced it and all the other bulbs at the same time since the car is old. Everything worked fine for a while but then the one in the trunk went out again and before I got home the rest of the lights on the quarter fender went out. Now the only working light is when I put my turn signal on or hit the brakes is that one bulb. The 3 running lights don't work. Any help or suggestions? What should I test with my volt meter? Is it a bad socket or ground? What would make all 3 of the running lights stop working on the rear passenger side of the car? Call me at 443-993-1568 if you need more details or have help.