Olive the cat

About a week ago I noticed Olive the cat had a bloody wound on the side of his head, under his ear. My sister gave me and Olive a ride to the emergency vet place and they said he had an absess there. It had to be cleaned out, costing a little over $700 - eeek! - all put on my credit card.

This is like what happened to Vicky.

We were supposed to keep him inside and clean and put hot compresses on the area, hopefully letting it drain and heal. It was worrisome because Olive has never been inside and I didn't know if he would even let me do things to him. Also, Yoda hates all other cats, so he had to be kept in my mom's old room.

It's now been a week and a day. Olive has let us do everything. The wound stopped draining a few days ago but we are still doing the hot compresses to aid healing. You can see the area here where they shaved behind and below his ear (his skin is gray and brown) ...

Now I'm not sure what to do. Olive is pretty old - he showed up here at least 11 years ago and was already an adult then, and he has become very thin and kind of weak. He may have some age-related problem like kidney failure, and the doc wanted to do a blood panel, but that would have cost $400 more and I just couldn't afford it.

Olive was probably attacked by another cat and couldn't really defend himself or run away because of his condition. If we put him back outside will he be ok? I don't know if Yoda and I can make it emotionally or financially with another indoor cat. I hate this.