Most likely whitespot, but no brackish water may be a contributing factor. Mollies seem to be more prone to stress in fresh water (especially if it's not hard alkaline water), so if water quality dips even a trace, if they're injured or bullied, they're often one of the first to show it. Stress weakens fish, and makes them more susceptible to diseases that they would usually shrug off, like whitespot. In my experience, mollies always seem to show stress by promptly getting ich.
If the fish is alone, or you can isolate it, making the tank brackish, even temporarily, may help treat it. There's a few threads in the brackish section that say treating ich in brackish tanks is often just a matter of raising or lowering the salinity a couple notches.
Hopefully you've reviewed your information on ammonia toxicity since your posts the other day and will take even a trace reading seriously.