It sounds to me like the parasite has gone through multiple life cycles in your tank and is reproducing rapidly. The only way you are going to be able to save your fish is to get them into a QT
and start either hypo or copper treatment. If the parasite has come back this many times it is going to continue to do so until it kills your fish.
My suggestion is to get the fish into QT
as quickly as possible. I know it's going to be tough to get them out of the tank, but it is necessary. Try taking out some of the LR
, that should help a lot.
After the fish are in QT
you will need to leave your main tank fallow for 6-8 weeks. This will allow the parasite to die off.
Good luck. I was in your situation once and it wasn't easy, but I definitely learned my lesson and have had a healthy tank ever since.