Brake lights and rear turn signals don't work

I have a 1999 Buick Century Custom and just noticed today that the 2 main brake lights and the rear turn signals don’t work. However, the third brake light up in the rear window DOES work. Additionally, all of the rear lights come on whenever I turn on my headlights.

I forgot to add: The hazards don’t work in the rear either. The front turn signals, headlights, high-beams, wipers, etc. work fine, the dash lights up as well. Searching around, this sounds like this might be a bad multifunction switch. I’m not a car guy, but is this something I could replace myself?