Thank you so much for your reply. Now I’m so worried that I may have made things worse for him. Since I already dosed with 1tsp per gallon, should I do a water change today and not replace any salt? That way I’d be removing the excess or should I still wait another three days to change it and still replace some..? Do I then keep water changes every four days or daily? Not sure if the four days is only initially or regularly. Sorry for all the questions. It’s just confusing with so many different opinions. I want to make sure I do what’s best for him or at least what may give him a good chance. That being said, what is your take on my current course of action — if salt is just an aid, is there anything else I should be doing instead or in addition to?Whatever you do, do not keep your Betta in one tablespoon per gallon of Aquarium Salt. This amount should be used of no more than 8-10 minutes' duration. It can also be lethal for a very weak fish. Sourced from too many to count but here's just one:
"Aquarium salt dip requires 1 table spoon per gallon of water. The time duration varies from 5 to 8 minutes depending on the severity. If the disease is related to fin rot or fungal infections, limit it to 5 minutes and for anything severe extend to 8 minutes.
"Important note: Never exceed the time duration over 8 minutes as it will decay your fish skin instead and burn its skin." (Emphasis mine)
Researching amounts to use for Bubbles' issues the recommended dose in not one teaspoon per gallon. It is one tablespoon per five gallons. That is around a half-teaspoon per gallon. Do a 50% water change after four days. As BettaLoverSara noted, replace only the amount you remove; IOW, remove a gallon and replace with one gallon with .5 teaspoons of salt.
Salt is also not a "cure." It is an aid in fighting diseases.