Are the lesions on the fish's body itself, or on the fins?
The red areas ( not exactly lesions ) are at the joints of the pectorals, so it IS on the body, not the fin. Interesting that as one side got worse, it started in exactly the same spot on the other side.
If they are on the body, you should run an online search for Uronema - you may be facing a protozoan infection, not a bacterial infection. This species of fish is really succeptable to Uronema.
If you decide that it is Uronema, do NOT use hyposalinity - that will only make the matter worse.
I will not use hypo until the Maracyn/PraziPro treatment is done, and then only if I see a need. If the infection does not clear up I will certainly look into symptoms and treatment for Uronema. Thanks for the warning.
How is the fish's breathing rate? If higher than 80 gill beats per minutes, it would be another reason to look towards Uronema as the culprit.
Breathing looks normal to me, but I have not timed it. Now that you have given me a "normal" rate of 80 I have something to measure it against.
From a quick Google search on Uronema, this does not look like it. The fish has had it over a week, but it is still very localized and there is no visible wound, and no scratching, and color is vibrant.
As for the head shaking thing, it may just be a trait of the species. I have another Singapore Angel in my reef that does the same thing. It is was the size of a quarter and scrawny when I got it 3 or 4 months ago, but has grown considerably, is now fat and sassy, eats well and seems as healthy as can be.