Help

Hi everyone, my betta has been very sick and battling finrot for some time now (i have posted on this reddit before about it, please check). I had to transport him on a 3 hour long ride to another city on Saturday and fasted him since, I put him in a hospital tank (with a heater + daily water changes of 40% + seachem prime) as soon as i arrived, i had given him his last dose of a second course of kanaplex last week on Wednesday, he unfortunately isn’t getting any better and i fear is deteriorating as he struggles to swim to the top and is laying sideways on the bottom of the tank and is very lethargic, his gills moving while breathing is the only indication of life, I have to leave overseas tomorrow evening and not coming back until the next Saturday, I am at a loss of what to do and i don’t have many options here, i have no one to watch over him while i am away and no pet stores will take him, please if you have any suggestions of what to give him to help with his sickness or the next steps to take i would greatly appreciate any advice.