Not eating

My big girl has not been eating for the past one week plus. Really no eating. Din eat breakfast, lunch and dinner. She has got total no appetite. I really afraid she will faint from hunger. But luckily she still willing to drink. So she drinks about 3 packet of milk per day. But those children milk in small packet. She is already so skinny, now even worse. Sometimes i can feel that she is hungry, but she refuse to admit so, and she refuse to take in any food. If we force her to eat, her face will turn pale, and she will cry. If we dont force her, all ok. Except that she will reach a stage whereby she will have no strength and no energy to do things. Probably just lie there, because of hunger. I really dun know how to deal with her. I shall wait another two days. After friday graduation concert, if she still give me this kind of nonsense, i will really force her to eat. How can go without food for weeks.