Can't eat anything, feel so weak :(

This whole week I haven't been able to eat a meal. I've already lost 12 lbs and feel so weak and shaky. I don't know what to do since I have blood work on Friday and I can barely stand up. I feel very nauseous every time my stomach growls and my hands and feet get very cold. I can't tell wether I'm hot or cold. I feel miserable because all food makes me nauseous. :( any recommendations from some of you all that have gone thru this, I could really use some help