This article details some common illnesses (common colds, allergies, headaches, flu, allergies, pink eye, diarrhea, stomach aches, and mononucleosis).  For each illness, potential causes are provided along with symptoms, treatment methods, and prevention methods.  The article is meant to serve as a starting point for diagnosing common symptoms that your child may be experiencing.  When you are sick, going to a primary care physician is always the best way to get a proper diagnosis, but this page can serve as a starting point for figuring out what the cause of your illness is.  

Princeton Common Illness Database