The kinked back is probably the result of an electrical issue in the pond, lightning, leaking electrical from pump or filter system, or other. Looking a the scales, I am not sure that I would attribute any swelling to a bacterial issue, but treatment of the ulcers should be high on the list. Of the products that you have mentioned on hand or available the only one that might be of any use for the bacterial infection is the Oxolinic Acid. I know of several that have used it and found it to be good. My experience is with Tricide Neo, which you will have to order online. If there has been flashing, piping, breaching or other activities indicating irritation, then the BSDT and the lice and anchor worm treatment, and a product for treatment of flukes like Fluke M or Prazi may be needed. The lice and anchor worm treatment is for parasites that are large enough to be visible without a microscope.
Zone 7 A/B
Keep your words sweet. You never know when you may have to eat them.
Richard