Stomach problems

The past few months I did eat less food. First I wasn't worried about why I was losing my appetite but now it bothers me. Because I am realizing the difference of my body now and then. My stomach was always hurting and whenever I ate food I felt like vomiting. Sometimes I threw up after I ate and I feel so weak whenever I do something now. It's hard to guess what's wrong with my body. I am not so sure what's really happening to me.

I know what you think! No, I am not pregnant. If, then I would probably gain weight, not losing weight. I am definitely not pregnant, as I have no boyfriend or husband so there's no way to get pregnant. I am losing weight without really knowing any reason. I feel so skinny now. I just hope this isn't a serious matter. I don't want to get sick, I just want a happy and healthy life. Just like what everyone of us wants. Maybe it is just the stress in school.