Hi,
I am not sure if I understand your situation and I know very little about your country but if your health worsens because of your stress or lack of nutrition you will not be able to help yourself or your parents or grandma either. From a practical point of view, it is pretty sure that the hospital you are getting your health care from has social workers that can take your case. From a deeper point of view and apologizing in advance for giving unwanted advice: Wonder Woman does not exist. You do not have superpowers, your body is suffering, this is the time to put yourself first because if you get sicker you will not be able to help anybody. I would justify your attitude maybe if instead of your parents you were talking about your children. Perhaps it is the time to tell your parents about your illness or get somebody else to support or help you. You need to be helped now. I am telling you this because I got a disability when I was a teen and had the tendency to refuse help and take care of others instead of giving due attention to my own health. It is a useless sacrifice