Either get some workers [might be really hard at this point though] or at least try to steal some brood of the same species from a different nest. If you can [might be hard since it's spring] try to get pupae. But be weary of Alate pupae, since they won't help much with the queen rearing new workers and are a real strain on resources.
Generally in colonies with a lot of worker force the queen becomes so very dependent on the workers that she does very poorly unless she has a large worker force with her to take care of her. The best you can do is brood boost and feed her and hope she makes it.