Yes on the Epsom salts. All info could be as mentioned above.
Do a pwc
and then Plain Epsom salts (ES), no additives and mix in up to a slightly above level tablespoon per gallon dissolved into water.
Leave enough room in the tank to add the water ES concentrate back in - use water conditioner /dechlor. any time you add in water.
Add concentrate in at about a 1/3rd at a time over the course of 12-18 hours. More quickly than I would normally but in an urgent or emergency it can be added in over a few hours if you feel the health is critical.
New to FW fish? First tank in a long time or EVER??? Need some info on keeping fish?
Start here - Aquarium Advice Article
FW Favorites right now Clown Loaches, any shrimp - SW Vase Red Mangroves