Hi David,
Sorry to hear! My best guess is Your dealing with a external bacteria infection. Any treatment You decide to use should be carried out for 8 to 10 days not 4.
Anyways I think the salt treatment will work well but again a minimum of 10 days no more no less. I would also use some type of dye mixed with Your salt treatment something like M-blue or acrflavin. another good choice would be maroxy IME.
Well keep Us posted and good luck
takecare
Cary Gld!