Hey how is your little friend doing? Give us update if you can. I hope he is better , but don't get discourage if something happened to him and he didn't survive. You was doing good job for him and sometimes no matter how hard we try the might not survive. They just like any human being can get sick and it hard for us to see them going. But you gave him love and clean water which is more then he would get in the store.
If he didn't survive you need to disinfect the tank if you will decide to rescue another betta. If you need nay instructions on disinfection let us know.