Irritable Bowel Syndrome
"I am not speaking from personal experience, but for my 12 year old son.  He started having stomach issues about 2 years ago.  His symptoms included bloating, gas pains, constipation, and diarrhea.  Sometimes the stomach pains would keep him up at night, unable to sleep.  We monitored his diet, and found that removing dairy helped, but did not eliminate the problem.  We, along with doctors determined he suffered from Irritable Bowel Syndrome.  A pediatric GI doctor recommended trying amitriptyline.  He started with a 10 mg dose each night which seemed to help.  After several months the dose was upped to 20 mg/night.  It has made a significant difference!  He sleeps well each night, and has not had a significant painful IBS flare up in almost a year!"