I haven't read the other replies so I hope I'm not repeating anything
It sounds like you might have an eating disorder. I went a week before without barely eating anything. At the end of the week I had an aching headache and struggled to walk. I began to eat healthy and started to run and felt a lot healthier and happier. Trust me, it gets better
I'm here for you if you ever need someone to talk to. It may be hard to overcome, but it can be done. If you need any advice or just someone to talk to about it you can
PM me any time^_^