Welcome to the Orchid Board. I agree with aliceinwl that the wise thing to do at this point would be to keep these plants separated from any others you may have. It would be really helpful to know how long you have had these plants and when in that time frame they started showing these symptoms. Have they been repotted since you got them? Also, what are your general growing conditions, i.e., indoors, outdoors (if outdoors, what is your climate?), watering schedule, how much light do they get, are you fertilizing, etc. There are many here who would like to help, but they will need more of the "big picture."