You can try a pedialyte soak just to provide some electrolytes since they are not eating. Use one part pedialyte to 10 parts spring water or dechlorinated water and allow them to sit in the water for about 15 minutes. Do it right in their hospital tank. Use their current water bowl since they are used to it. Then rinse it out and return to using regular spring water or dechlorinated water.
Any idea of which meds your vet is prescribing yet?