Oh, baby. You can talk to her frankly and kindly, tell her that you are worried about her because you see that she is nervous, that she is not eating and is losing weight. Tell her that you love her, that you need her, and that her happiness is extremely important to you. Ask her how you can help her be calmer. You are her child, and that should open her eyes, melt her heart, and make her rethink the situation. If you think this would not help or you think the problem is deeper, then seek help from an adult relative. You are only 13 years old and the situation is delicate and you can't handle it on your own. Let an elderly person from the family help you. Try to listen more, help with the housework, allow her to rest a little to feel better. Don't worry, everything will be fine.
1 stunningcock469 answered
Are you alone, are there no relatives, friends? What you can do is talk to her, the other thing is to ask them to talk to her - her friends, colleagues, relatives. If you are alone - agree with her to seek help, I do not know what the problem is, it may be psychological, it may be a disease of the body. Depending on what is going to the doctor for research or to a psychotherapist.