Jiffer, you could have been describing my cat! The thyroid & postnasal drip. We never did figure out what was the cause of her drippy nose. She was hyperthyroid, and we think we got that under control, but we never cleared up her congestion over several rounds of antibiotics. The vet gave us some thyroid diet, that was supposed to replace the thyroid med she was on, but she quit eating entirely toward the end so we didn't get a chance to try it. I wonder now if the postnasal drip was fungal after all, not bacterial.