Keep him clean and as comfortable as you can, as I know you are already doing. He has been retreating for some time==yeah? Sometimes meds just make it prolong and increasing the agony.
I always kick myself because my Bettas don't live to five or six. So far I now have one--my last of Synirr's original minis-- that he is probably going on two. He is still fiesty. I wonder if I could have cared for them better and they would have lived significantly longer. But really some were well cared for, never waited signifcantly for a water change, and they died after a few months. ??? I just keep tryingto get it right;
And I know that your old men do much better than mine.
He has just eaten one bloodworm. I defrosted some today and held one on a cocktail stick until he noticed it and then wiggled it at him and he ate it. He wouldn't do it twice though.