I'd go ahead and try the peas after you change his water, it can't hurt. If he's making a bubble nest it's hard for me to think it's dropsy, I would think he'd be rather listless, but I suppose it's possible. If it is dropsy and he is still bubblenesting, it's a good sign that it's in the early stages and you might be able to treat it. Usually they completely stop eating when it's dropsy too, so if he just won't even eat at all, I'd move on to trying some Maracyn-Two.