Check the loom of wires inside the trunk by the driver's side trunk hinge. Open up that loom and check for broken or frayed wires inside there. That's another known trouble area on all the Camrys. Those wires are exposed to a lot of flexing as the trunk is constantly opened and closed through the years. Eventually those wires break.
I wouldn't hang your head in shame, I would neve have thought 3 bulbs out at the same time either. In fact, I don't know if I have ever seen that. It is not impossible, just not probable. But hey, at least you got it figured out and fixed :clap:
That is highly unusual. I would check the output of your alternator to make sure it is not overcharging. Sometimes the internal regulator can go bad causing the alternator to overcharge. Burned out bulbs could be a symptom of that. Many auto parts stores will check the battery and alternator for free while still on the car. Autozone offers this free service. If you don't have an Autozone in your area, I would make a few calls to other auto parts stores and ask if they offer this free service.