This betta is currently being treated with bacterial, fungus and parasite medication.
He had no signs of ick, but it does look like he has had some gill flukes come out after being medicated.
Does the area where the yellow lines point to look like a location where the scales have come off or a location where a parasite that could not be seen came out of since it looks indented to me?
He has also been in a hospital tank so there is no way it could have been caused by injury. From pictures I took and looking at him as closely as possible this is something that only cropped up after he had started to be treated and not before.