Help me save my cat Blackie

Hello everyone! This is my sweet boy Blackie. I live in the Sunnyside neighborhood, I’ve been a resident all my life. On April 14th, my sweet boy came home with a  burn scab on his left ear, I cleaned it up as best as I could. On April 15th, he came home with whiskers missing from his right eyebrow. A few hours later continuously vomiting. He refused to eat or drink anything, he would zone out. April 16, I spent my entire birthday with him at an emergency vet & had to leave him overnight. Today, April 17, his vet has called me a couple of times to inform me he is not getting any better. She recommended that he stay at the hospital and needs more treatments like an ultrasound, possibly surgery. I believe that someone did this to my sweet boy. He has been an outdoor/indoor kitty for 2 years, never had wounds like this. I’m asking my community for help, help me save my cat. I’ve already dropped $3000 for the first treatment. And I’m worried I’ll have to bring him home to be in pain. Thank you all for any help you may be able to do.