Green stool, clear urine, pain, nausea 3 months after gallbladder removal I AM DESPERATE

I am a 16 year old girl who for the most part was healthy prior to the start of my digestive problems.   I am 5"3 and have never weighed over 99 lbs but my weight has now dropped to below 94 lbs due to inability to eat without pain and nausea.  Around August 2011, I started having moderate-severe nausea and abdominal pain following most/all meals, which over time progressed to be nearly constant pain and nausea that made eating nearly unbearable.  Starting in early March, I had multiple blood tests, an ultrasound, a HIDA scan, and an upper endoscopy.  The only explanation offered to my mother (a doctor) and myself was that my gallbladder was hyperactive and excreted bile way too quickly, with an ejection fraction of 89%.  Normal ejection fractions are considered to be roughly between 30-75%, but high ejection fractions are a gray area in the medical world at the moment, as most bad gallbladders have a low ejection fraction.  All the children's surgeons refused to take out my gallbladder for this reason, but with it being our only hope we searched for a surgeon willing to take the chance.  We were luckily able to find a surgeon with some knowledge of hyperactive gallbladders who removed my gallbladder in early May.  My surgery went well and there were no complications immediately following.  I did not have constant diarrhea following my procedure and my pain and nausea were alleviated until approximately early-mid June.   I began having moderate nausea and pain again following nearly all foods and some drinks such as slushies or shakes.  It increasingly worsened but has not yet reached the constant pain/nausea i was experiencing pre-surgery.  I also had approximately 3-5 bouts that lasted about 10-20 minutes of extreme nearly unbearable pain, usually in my left abdomen just below the ribs approximately 20-30 minutes after I had eaten.  Each time brought me to the floor and to tears.  I visited the GI doctor again July 5 and was told their best explanation was Functional Dyspepsia and that I should begin taking 30g Amitriptyline each night.  I was told results should appear approximately 3 weeks after I start regular dosage, which I did on July 5.  I have seen some improvement in my pain and nausea as they do not necessarily occur after every single time I eat anymore, but they are still way too frequent and persistent for me to feel normal, much less function normally.  Over the past week or so, my stools have been a bright green color and my urine has been clear for the most part. There seems to be no connection between my symptoms and my hormones as they do not worsen or alleviate with my menstrual cycle.   I am sick and tired of being so sick and tired as my symptoms have majorly impacted my life and prevented me from participating in many things as they caused me to miss over 40 days of school just since January 2012.  Please please please offer any ideas or thoughts you might have, i truly am desperate.