My 7 Year Old Constantly Battles With Severe Diarheaa And

My 7 year old constantly battles with severe diarheaa and vomiting, major stomach pain. The only diagnosis I am ever given is constipation and I am very skeptical of that at this point. It is affecting the quality of her life and, quite frankly, scaring me to death. What should I do to help her and to help a Dr understand the severity of the situation? I'm worried it is something life threatening that is being overlooked.