try not to worry too much, wait until you can get some answers from the vet tomorrow. Whatever the outcome though the vet will understand your situation. My mum had to have her cat put to sleep a month ago, his kidneys were failing and everything was starting to shut down. the vet suggested some things they could do to extend his life but understood and supported mum's decision to have him euthanised, due to the cost of treatment just for a few more months of life (he was an old cat anyway). So, long story short, they will understand, whatever decision you need to make.

fingers crossed for you that it's something simple to fix