Fungal and bacterial infections can at times be difficult to distinguish. Both can have fast moving black or brown spots (sometimes stinky/moist/mushy) on the leaves. If infection spreads to the crown the leaves will often drop off suddenly. The difference between fungal/bacterial and viral infections is often the speed with which they appear and spread. The spots on leaves from a viral infection often appear much more slowly and the plant slowly tends to lose vigor.
If the leaves are floppy, it is often a moisture or root problem. Are the leaves wrinkled? What kind of growing medium are you using? Where are you growing (windowsill, greenhouse, etc.)? One thing about Phals is that they like to be evenly moist, not dry out too much. It is possible they are getting too dry if you are not watering until they are really dry. How do the roots look? Are they thick with greeen tips and get green when watered, or are they brown, mushy, or dry and wrinkled? When was the last time they were repotted?
Photos of the plants will likely give a better indication of what is going on.