This was all very normal for me, and when I get anxious, I slide right back into it.

So listen, medicine tastes bad, and that makes you not want to take it. Anyone here that know better than be is welcome to contradict me, but meditation or "mindfulness" as a practice is designed to combat exactly your problem, to the tee. You don't think it is for you? You are wrong. You've got a runaway brain and don't know what you are talking about.

I'm making a harsh appeal to your intellectual brain instead of your misfiring emotional brain which doesn't want to take a yucky medicine.

IMO, the best thing subsiquent poster can do is keep it simple and sound off helping to drive this single point home.

I feel like I just need to chill for a while. Meditate, watch videos (nothing mentally active, I feel making decisions makes it worse) etc..
I can't understand why. This is why I didn't think the usual would work.

Any opinions about why this happens?
To me it usually happens when I do a lot of mentally straining stuff or plan to do something big. This could be ego depletion (but sugary food usually helps with that, not in this case) or this could be some sort of an emotional/mental thing that clears up when you do nothing.