It's quite possible the issue to have started with parasitic disease and then progressed on to bacterial of some sort as well based on the info you gave(flicking and the external signs). I can't comment on Esha but Melafix and Primafix may not solve an advanced disease and can hardly have any effect on parasitic infections. Maybe you need to try a broad med that treats both parasites and bacterial issues, if not, try an antiparasitic med followed by antibacterial again, but different ingredients if Myxazin didn't work.