Need help/first aid for my cat

My cat has just gotten home on Feb. 19 after being catheterized and he refuses to eat after so I tried to syringe-feed him earlier today for three different times at 3pm, 5pm and 9pm with 10ml of Royal Canin Recovery. Then at 11:18pm today, he started vomiting, the color was the food that I fed him and now at 1:03am, he started pooping white liquid, maybe because he hasn't eaten anything. Everything happened so fast I don't know what to do. I don't know what these symptoms are. I'm really worried about him. I was hopeful because I was able to bring him home and he was on the way to recovery after being confined at the vet for 9 days because of a urinary blockage and now another problem arises. Please help me on what do I need to do. I'll try to bring him to a vet first thing in the morning, I'll look for ones open on Sunday because I'm really worried about him. But please help on what can I do for now to help him.