What is wrong with me?

Lately, I haven't been eating a whole lot, When I look at food I want to throw up, So basically I have lost my appetite, I've only had A granola bar since 2 days ago, I'm worried about my body.. Am I sick?
(And before you tell me I'm starving myself, I'm not. P-P) I've also been feeling really weak since this has happened.
What is wrong with me?
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