Read the entire post again.
Even if this is scale rot, which is very seriously doubted, then it has progressed to the point of being systematic and does need stronger meds. (I don't see any signs of scalerot on the side scales) That and the bad spot, where you can see the hottest spot was, whether hot rock or bulb.(unknown)
Incedentally, the internal meds AND the topicals for the treatment are basically the same for a burn as scalerot.