About yesterday, no idea. Today's sharp drop was as Trum was giving a speech (and later answering questions) in Davos (via teleconference). He said something along the lines of: "I've been talking to the Prince of Saudi Arabia and I've told him that oil prices have to go down a lot". That was your (lucky) spike down.
Nice, thanks for the intel! I'm still very much learning how oil works, but I figured there must be a specific catalyst for a move like that.