It seems to be Powdery Mildew, the best thing is to remove the leaves that are completely infected to prevent it from spreading to the rest of the plant, and start using Neem Oil and Potassium Soap, use it after wetting the plant to remove the fungus and as a foliar spray once a week until it’s gone. It’s contaminated, but with dedication and these care tips, you’ll get the plant back on track.
Another option is to get some organic fungicide, although almost all of them are based on oil or Neem extract.