14M, very thin, struggling with extreme loss of apetite for months now. sometimes i get so hungry that it physically hurts and makes me dizzy, but for some reason i just simply refuse to eat anything. been skipping breakfast and dinner for about 2 and a half weeks now, im scared. my ribs are somewhat visible and the bottom of my ribcage pokes out like a sore thumb. my skin is ghastly pale on most days too. i get headaches often and sometimes nausea. i just dont like eating. 

any advice?