Manage to get him to the vet, but unable afford some testing and needed treatment at present, yet I just got my job back. In the meantime, Simba is on a diet of wet food with some water with low protein/phospherous and some such to alleviate his renal inefficiency. Also giving some anti-nausea meds and this powder stuff to mix with wet food replace missing nutrients from low-protein diet. It has minimized his vomiting to once a day or two, and is kept hydrated, if going to the litter all the time is an indicator only with kidney issue.
Beyond that, remember now how Simba can be annoying, lol. He has the habit of knocking things over and off shelves to get my attention for food or just attention, made worse with needing to feeding him only small portion every few hours. Rarely been having full 5+ hours straight sleep.
He appears his usual cat self when not sick.
Now searching cost alternatives as cannot always afford getting wet food from the vet. If he can wait couple more weeks, can afford the some further tests, and then figure out from there. I have emotionally resolved that if it is something lots of money to treat just to get him another year or so of deteriorating health, will unfortunately have to say goodbye to him once things get worse for him.