Thanks for your replies, everyone.

I feel a lot better since being off my Rexulti. Getting less sleep (7-8 hours instead of 9-10) and don't feel worn out. I'm also feeling more upbeat.

I took your suggestion, still_crazy, and looked up the half-life. Rexulti's half-life is 91 hours! It's been well over 91 hours at this point, though, so I'm pretty sure it's out of my system by now.