Discus can tolerate any med. Make sure other fish in the tank can tolerate the med.
Wonder tonic, Blue circle white spot cure and Malform will all do the job.
When treating with salt you have to watch your plants. Too high a dose will kill the plants.
I've been keeping and breeding discus for 30+ years and have not have a discus with white spot. I would get rid of the neons and replace them with cardinals.
Ron