I noticed my cats was dry heaving and throwing up colourless liquid with a bit of foam (occasionally) and thought he had a hairball. However, I found some thrown up food in the litter box twice now (I don't know why there). He didn't want to eat as if he was scared to almost? I managed to get him to eat some yoghurt and them some pate, eventually him feeling confident to eat wet food. But that's also thrown up. He's not meowing, but acting normal apart from the sudden heat rise we've had. This has been going on for a day and a half now and I've contacted the vet who told me to monitor him, but I'm concerned about him not keeping the food down. Any ideas?