I am 13 and have not ate in 3 days?

Well I am 13 an I have not ate in 3 days. My mom said if I don't seen is sending me to St. Lawrence Psychiatric Center. But I just any eat. Plzz help me what should I do? I am scared and know I need help but I am not the kind of person to open up to people. Also I am starting to think my mom is right. And before I stoped eating a wade 182 now I way 153 :/ plzz help :(