Was it raining when you drove it home? Used to have a car (I think '04 or '14 Alero) that was notorious for getting fucky when the wiring harness in the front tire(s) got wet. I don't remember what warning it set off, but replacing the wires was only a short-term solution because all it took was a good rain for it to get fucked up again.
My son has been provided a safe/quiet space to remove himself to and the option to go there when he feels it necessary as part of his IEP. It's been a huge help and he's been needing it less as he gets older. It doesn't really solve problems, but it definitely helps prevent them from cropping up or spiraling out of control as often.
Sensory toys/fidgets are good too. It helps divert some of that frantic brain activity so it becomes more manageable.
Add a waterpik into the mix. It doesn't replace actual flossing but can be really helpful as a supplement, especially in hard-to-reach areas.
You should give a shit if you want to keep your teeth. You know your jaw itself can erode from gum disease? Been there, done that, and now my dentist has been nagging me for years to let them yank out 4 teeth and put in a bridge because they're so unstable - and I routinely have dreams about all of my teeth falling out.