Q. My 6 yo cat vomited a hairball & also had diarrhoea. Since then she hasn't eaten more than a couple of mouthfuls of food, no faeces & little urine
DAVID ELBEZE, DVM, MRCVS
A. She might have an intestinal blockage due to hairball blocking the passage of food.
I would recommend not to wait, neither to start hairball treatment which could take time to start working as it sounds like it might be advanced and life threatening.
I advise you to take your cat to your veterinarian for a check and together decide what would be the best course of treatment.