I agree. [And not just the blood. Even if something like this has happened or will happen in his future none of this makes any sense. Not just why he would attack Jack but why he wouldn't be able to remember any of it later.]
Do you think there's a chance that whatever happened has more to do with this place than you? That it's one of their tricks? [As far as tricks go making him kill someone he cares about seems particularly brutal even for this place.]