Answer:
I would say she may have an eating disorder; shes not eating enough, which is causing her body to not have enough energy to mantain basic functions like sleeping and why shes losing weight all of a sudden. It would cause her body to no longer grow properly. She may also be drinking water instead of consuming food which is why she is constantly thirsty and has to urinate so often.
im not 100% positive in my answer but i have a very stong feeling.