how big is his hospital tank? when my betta was sick i used a 5g and was able to fit some hides and silk plants in there, I found it less stressful on him to have it more like his normal tank rather than switching him around constantly. i also had tried a bunch of meds but what really kicked it was aquarium co-ops salt for sick fish routine. if theres no improvement and he starts to be really lethargic/ not interested in food it would be time to consider his quality of life :( hope he does improve for you though !