I have a 12 year old son who, since mid February, has had stomach issues. No appetite, cramping, nausea, some vomiting but not too much. Today he came home from school and said his back hurts and he cannot bend over or even to the side. He did have shots at school yesterday. His symptoms are so strange because he seems fine one day and the next he's sick again. No fever that we have noticed but at times looks very pale.