I'm thirteen years old and have been having nausea for about two weeks now. I get it whenever I work out, whenever I eat or when I stand up too quickly. It gets so bad I have to stop moving and jist lay down. I have also been having pains in my stomach, almost like stabbing pain that happen randomly but can last for a few second to a couple minutes. I have been getting headaches that feel like I haven't had enough sleep but I'm sleeping fine. But, then sometimes the headaches are stabbing pains. And lastly, yesterday I woke up with a sore throat and have had it since. What could this be?