I don't know anything about putting Baytril in the water. But my guinea pigs were in the same condition as your girl. They were both active, ate, drank, lungs were fine and were acting completely normal but one had crust on his eyes and the other sometimes had crust on his nose. So the vet put them on Baytril by syringe and within two days, one of my pigs stopped eating and had diarrehea. I thought he was going to die. I do believe that Baytril is too hard on guinea pigs, especially when it is not certain if there is anything wrong with them. My one pig still has crusty eyes, he has had this since I got him in January. I know guinea pigs can go downhill fast but I really think that because of this we sometimes act too quickly at diagnosing them. I believe the Baytril has permanently damaged my guinea pig Coco, whose poops seem to constantly change in composition and size, and his stomach can't handle some of the fruit they it used to. Maybe your vet is right in his technique with your girl.