Looks more like velvet (fungus).
I just started treating a betta for a patch too, luckily she still eats, and had a nice fat maggot for dinner.
I'm using TetraMedica fungistop which is silver based. You need to set up your hospital tank with aged water, as dechlorinators have chelating agents that binds heavy metals.
She seems to be getting the first signs of dropsy too.
I think you can get the Kordon Itch medication over there that is not available here, someone will pitch in shortly to tell you which one. One is more gentle....