Melafix is a antibiotic not really too much of a anti fungal.

Quote From wikipedia
"Melafix (a proprietary name) is an all-natural aquariumantibiotic consisting of an essential oil of the Melaleuca genus. Contrary to popular opinion it is not made from the common Tea tree, Melaleuca alternifolia, but from Melaleuca leucadendra, also known as the Cajeput Tree. This is confirmed by the manufacturer's Safety Data Sheet.[1]It is a wide-range antibiotic product, and thus is effective for a wide variety of mild gram positive[2] bacterial infections, such as fin rot. However, it is generally ineffective against aquatic parasites and is typically used for treating the wounds caused by them in order to prevent secondary infection by other microorganisms.[3]"

So you are helping the frogs own immune system to fight the fungal infection. This will work but it will take longer.

And be careful not to confuse "calmness" with lethargy.

Is the frog actively hunting crickets , better yet does it have an appetite, also has it had a Bowel movement in the last few days.

I am very surprised that non of the other regulars haven't chimed in like Lija and Colleen