Myxazin mainly treats the bacteria in the water.
Anti internal bacteria med by intepet treats the fish inside.
The waterlife meds is for parasites.
Lumps can be internal bacteria as they are filled with fluids.
I would try another round of the interpet med, if no change will have to look into something else.
The problem is the healthy fish will start to build a resistance up to meds, so if they ever become ill the med might not work, that's why is always best to issolate sick fish.
You could buy the waterlife med myxazin it's up to you.