Yeah, don't go after the flagellates unless you actually know they're there. Fasting and weight loss are normal this time of year. And lime green poops are actually urates.

(To date I've had to treat three snakes for flagellates: two in early 2009, one in early 2010. It does involve a month or two of rebounding as the digestive tract recovers, and my 2nd pied spent several extra months producing The World's Smelliest Poops. But everyone recovered their appetites within a couple weeks of the first treatment.)