Good advice in this thread!
Also, check closely for pill bugs, sow bugs, millipedes, and other critters that might nibble on the roots, and look closely at those leaves to see if some of them might be scale. You might need a magnifying glass, or jeweler's loupe (I have a 4X) to see them more clearly and closely.
After it's cleaned up, and re potted in pure LFS, and set in a high humid area for a few weeks, it should make a fine recovery. - Rich