Since it's been a month, and drool is never good. BG thinks the best thing for this animal right now is making sure the temps and humidity are right, and take it to a QUALIFIED VET ASAP. A Qualified VET can tell him how to care for it properly.
Big Gunns doesn't think that animals "usually" go off feed for lack of "safety"(it is a cause though). It's usually husbandry(which can include "safety") that's the problem. Temps and food it basically doesn't "like" are bigger problems when it comes to a Water Monitor. BG does agree that a scared animal may go off feed though.
Get this animal to a Vet ASAP.