What if he was spiked? As in hemalurgy? This could explain his sudden change of temperament.
From here: http://www.17thshard.com/forum/topic/7267-words-of-brandon-compiled-x-2/
"Q: Would a Hemalurgic spike take surges? A: Hemalurgy can interact with every one of the magics. I designed it specifically in writing Mistborn for future use. Because some of the magics are so limited by their planet I wanted one that transcended all of them and Hemalurgy is very important to the entire Cosmere Its invention is a thing of great power and great danger to the entire Cosmere. Q: Have people not from/on Scadrial used Hemalurgy? A: Yes."