begonia sad?

Hi All!
I have had this B. maculata plant for about a year now and it’s looking worse for the wear. The first two pictures are the begonia now and the last one is when I got it. The leaves are looking red and curled in on themselves and the stem has turned brown. What can I do to help this plant? I have been trying to keep it in indirect light and I water it about once a week. Sometimes i also put a plastic bag with some water drops in it on top of the plant to create a moisture dome and keep the humidity up because I live in a dry area. Nevertheless, my begonia isn’t looking too good and I want to give it some help to grow big and strong. Any help is appreciated! Thanks!