This may sound "out there", but try this. I worked as a massage therapist for years, and there is often healing power in one's hands that can heal pain and work wonders. If you can hold your hands on opposite places,* not necessarily even touching your cat but close, for some minutes. Especially over the organs that are having difficulty. Try at several opposite places.
I have helped many people with terrible pain this way; it may help. It encourages the healing power of the body. Try relaxing your hands while doing it, and relaxing your own mind and body. And, of course, praying inside at the same time.
*Meaning opposite places on your cat - like the right and left side, so your hands are facing each other with the cat in between.
So....how's the kitty doing?