I will say this after reading the story of what's wrong with him...and this is just my humble opinion, nothing more...but I think you should start thinking about what you'll do if this doesn't get better. 6 days of not eating, and then being force fed, and the throwing up what you were force fed, that's...brutal. And I genuinely hope he gets better. BUT. You have to consider how long you're willing to wait, hoping it will. Because in the meantime, he's suffering. I sincerely understand how hard it is to put a pet down, i've had to do it myself. It will absolutely rip your heart out. But at the same time, you can't let something you love suffer because you don't think you can stand to be without them. And again, i'm not saying give up right this second. I'm just saying you're already happy and willing to take care of the cat in the event he does get better. So you're prepared there. You might want to also prepare for if he doesn't.