I was able to view videos.
What is age of tank?
What test kits are you using?
How were fish acclimated wen you got them.
My thoughts are Lymphocystis and the good news is that its' viral. The Bad news is that it is spreading and generally spreads quickly. Infection appears on the infected fish as one or more white or beige colored pebble or wart-like nodules most commonly seen on the fins, skin, or gills, although other tissues may be affected.
It is usually found in the fish skin and fins. After residing on its host for 4 weeks or more, the Lymphocystis cells rupture or fall off the host, spreading the infected cells in the water. The cells then either sink to the bottom of the tank and lie dormant or reattach to another host via a break in the skin or fins, or in the gills.
The good news is this virus is unique and is fairly easy to identify, and death from the virus itself is fairly rare. When the virus first begins to grow, it may be confused with the parasites Cryptocaryon irritans (marine white spot disease), appearing as small white or off-white specks on the fish's skin or fins.
There is no known cure for lympho , but you can utilize ruby Rally Pro to give a little relief.
Is is imperitive that you maintain good water conditions and diet of these fish are going to heal.
Back to the fish- Is this tank New?
What is ammonia-nitrate-ph - salinity of tank ?