The water dragons probably did not get the proper nutrition and have some calcium deficiency, so the fact that one may be gravid makes the matter worse. Try to orally administer some cruched fruit-flavored Tums with your finger to each one every day. As for the frilly, they don't do too much except bask and eat, so as long as it looks perky with its head raised and its eyes clear then you shouldn't worry. I would also place him in something a little bigger, probably a 55 gallon or so.