All of my days are just filled with grief

For the past few months everything has been worse for me. No matter what I do i am constantly surrounded by this feeling of not being good enough, good enough for my friends, good enough for my family, good enough for myself. It always feels like there's this Monster running in my head which makes me think about the bad aspects of everything I do. I feel like I am doing my own bad. It's making my days worse because not even an hour passes by in which i am not tensed by something. Even the little things are bothering me and because of which my relationship with my friends and my family is getting adversely affected. I really want to improve everything and become the best version of myself.