This is my theory, and it may be all wet. But here goes. When we initially captured him, he was highly stressed, did his laps around the cat room ON THE WALLS AND EVEN THE CEILING! He laid in one spot panting so hard all night, even after he quit running, I was afraid he would stroke out.
Then in the middle of the night he squeezed himself behind the trellis that was in front of the window, jumped to the roof and vanished for a few weeks.
When I finally saw him again, it was evident he had been in a fight or two. I let him stay around here without grabbing him up, but the other day, it was clear he needed to go to the vet, so I snatched him and carried him upstairs.
He only went ballistic the first night, and until we covered the window with chicken wire, we were afraid he would escape again. Now, I believe he understands I am trying to help him. He has to be feeling better, his eyes are clearing up, his ears aren't caked with dried blood, he is getting regular meals and this morning we let him out of quarantine and he has the entire second floor to prowl now. He has found refuge in my canning cupboard, I suppose because it reminds him of places he used to hide, old abandoned sheds etc..
He is so tolerant and loving, and were it not for his initial capture behavior, I would almost say he was a neglected stray. But strays don't usually go ballistic and launch themselves at the walls. They get anxious and meow, and scratch but they don't go into orbit when captured.
And yes, unless the good fairy intervenes
Mike and i pay for all treatment out of our pockets.
One more thing, if you make these animals understand that they are dependant on you for everything, food water, etc.. and take away a certain amount of their freedom, they will come to trust you as long as you don't hurt them. Hurt them one time, inadvertently or otherwise and watch out- you will be the one hurting before the cat is through with you.