i keep all my bettas in glas containers of different kinds, i do not know the ph value but i intend to get a kit, they have fake plants, after a bad experience with some killer gravel i use exclusevely glass marbels and i have a bit of java moss in every tank, i change the water often several...
give him lots of water changes, remove any uneaten food to keep water clean, when you do get to go the store there are antibiotics the fish eat that help
i recently lost an awesome crown tail mail,hyper and macho, looked like a tie dye shirt of blue and red to laziness and lack of any zest for life.
he would flare at any one or anything for any reason unless you said boo then he chickened and swam away as fast as he could go.
I had named him Odin...