Guessing you have done a number of water changes to dilute that Melafix mishap.
Keep monitoring the water quality yo make sure it remai s in a safe zone, and do pwc
's if it is mot safe.
Keep doing the water changes until safe again.
Many fish which have a marvle or speckled coloring can continue to change while maturing. Gf, Bettas, and Mollies.
Watch for Ich. Speckles can look similar.
Clamped fins, lethargy, and hiding alone, not eating, are all signs the fish doesn't feel well.
Watch and see if the whiter places on the fishes body look grey tan, fuzzy or peeling also illness signs.