sounds like a fungus starting............I would try this mix after the sun passes if it not to large & the fig has cooled off........mix 1 qt tap water 2 tablespoons dawn & 2 DROPS vinegar and wipe the leaves on both sides.
If you have washable ceilings, I made a mix up of 1 gallon of warm water, 1 tablespoon dawn, 1 cup vinegar, 1 tablespoon lestoil and used those new style cleaning clothes.........they came up so white and clean. what a difference.