Why do i keep feeling this way?

Lately i've been feeling like hot all over my body, but like i wont sweat, n sometimes my feet will feel numb. Also i get these weird stomach cramps all over my stomach. I get like light headed, n when i get up fast i get dizzy n like things get dark (not like pitch black i can still kinda c things, its just dark) Also i get really tired n i jst want to lay n bed. But its hard for me to fall asleep. N no i can not b prego cuz i am 16 n a virgin. could it b this new diet im on?? im trying to cut dwn on meals. The main meal i eat is lunch. I dont eat breakfast, instead i drink water. I try not to snack n if i do jst a couple of chips or so. N for dinner ill eat like an orange, or cereal. People tell me im not eating, but technically im still eating. So wat could b causing this?