Should I be worried about my strange eating habit?

For the past month I havent been able to eat much, I never eat breakfast anymore if I do I always feel like throwing up, I eat very little at school for lunch even if I do eat, and for dinner, I eat alot less than I usually could. I couldnt even finish half a sandwhich the other night, and it was a normal sized sandwhich mind you. Im not ually active so we can rule out pregnancy lol Im just startin to get worried and my Mom gets mad cuz I dont hardly eat. Please help?