Domestic medium hair (orange and white) Male just about to turn 6 yrs old Neutered 12-14lbs Central California

He was a rescue at 10 weeks old. He was small. Abandoned by mother. Rescue placed him with another momma cat to nurse and it went well.

Never been sick aside from one night months ago where he was vomiting large puddles every 2 feet about a dozen times or more. I followed him around with bath towels until it ceased. He seemed fine otherwise. I thought that he got into my dogs wet food and it made him sick as thats what the vomit looked like. I remember thinking it was very out of the ordinary as he doesn't even cough up hairballs. He normally had stinky stinky man cat poop. And he was at times gassy...like boxer gassy. And belched like a human man.

A few days ago he started seaming lethargic and not his lively self. I got concerned on day 3 as he wasn't getting better and was now hiding in the bathroom and not moving far. I took his temp. He had a fever of 103.1 his gums were white and slightly jaundiced. Took him to emergency vet. They did blood work and a urinalysis and another panel of tests, an ekg, echocardiograhm ultrasound. His rbc was 12%. They did a blood transfusion which brought it up to 20% but within 2 hours it was back down to 18%. He also had a uti. Enlarged spleen (the largest they personally had ever seen). He had a good amount of fluid in his thoracic cavity and his spleen. Negative fiv/felv. The dr said his prognosis was not good and was guarded. She suspected cancer. They gave him fluids, bp fluids, antibiotics, steroids, pain med, medicine to keep his blood from getting too thick or thin (?) After spending 7,000.00 and watching him decline and not being himself and being told that everything that they were doing should have perked him up a bit and that fluid would probably continue to build up and rbcs would probably continue to decline...we decided to let him go. I am devastated and wondering if I missed something or if this could have been fixed. I have a 19 year old bag of bones of a cat who has kidney disease and I really was prepared for something like this to happen to her. Not that I want it to but that it was my young seemingly healthy cat was a shock and I can't wrap my brain around it.

What was going on with my cat? Did I do the right thing? What makes it even harder is my teen got this cat from us when he was 10 as he really loved orange cats. My son has autism level 1. He understood what was going on but it is still challenging for him in a way that is different from someone who is not autistic. And it adds to the heartbreak. We all loved this cat so much .

Thank you and please forgive me. I am new here and hurting. Please don't be mean.