iPhone 4s: No sound, flickering screen, black screens, and more?

Ever since yesterday, my iPhone 4S has been giving me really weird glitches, progressing more and more towards the worst ones. Allow me to list them, in order of occurance:

1. Started with my E-mail: Unknown Sender, Unknown Subject, Date: 12/31/69
2. Audio refused to play from external speaker. Slient mode off, volume maximized, tested across various apps, headphones unplugged/replugged/unplugged. Fixed itself after reboot.
3. Random black screens with swirling loading circle icon. After a few seconds, it returned back to where I was.
4. Recieved a text message. After unlocking phone, screen began to flicker. Various gadgets from the pull down notification center appear in landscape, lockscreen background appears in portrait mode— all of them flashing, strobing, and distorted— until it went to a black screen w/ circle icon again. After a few seconds, returned back to unlocked lock screen.

Any ideas?

I haven't dropped it, and it was never dropped into water or anything.