What should I do if I can't stand how my body looks right now?
I'm sorry you feel that way. What is it that you dislike about your body?
I'm upset about myself and sometimes I want to stab myself with a knife
While it is not good to want to hurt yourself, it is normal that sometimes you won't like parts of your body and that you notice things about it that others don't since you feel all the aches and pains. It would be good to do things that will make you feel better.
I have to ignore it. I can't be bothered with other things.
Everyone has physical imperfections that they might like to fix. It's okay to notice your own. Just take small steps to improve it.