What medicine did you buy?
I dont usually use commercial sold medicines.
I prefer the 1 table spoon of non iodized table salt per half gal. method.
But if you do, Melafix and pimafix is good.
In combination with daily water change of 50%.
And if you have access to dried banana leaves...
Could be the marbles. In that case transfer the fish to another tank with old clean water. Put a small pice of dried banana, manggo leaf. or a tablespoon of non iodized table salt.
Or try flaring him with another betta :)
What kind of live food.
Try to get from clean food stocks or clean them before giving it to your bettas.
And not too much :) Your water quality will suffer.
Hi Katie!
Im new here, but Ive been keeping and breeding Bettas.
Your fish is probably stressed from to much flaring :)
Your bettas need lots of alone time so they can rest.
And a minimum of or every other 3 days water change 50-100 percent.