If you have been unable to eat or keep food down for three days and are feeling worried, it may be a good idea to consult a healthcare professional. It is important to stay hydrated and watch out for signs of dehydration, such as dry mouth, decreased urination, rapid heartbeat, fatigue, and cold hands and feet. Taking something for nausea and trying to eat easily digestible foods like white bread, white rice, bananas, and applesauce can also help. It's important to address the root cause of your symptoms and seek medical attention if they persist.