PLEASE Help!! Yellow Stool for a month!

Any help or responses would be GREATLY appreciated.

I'm a 21 year old female who despite being overweight (180 lbs)  has not experienced many health problems outside of common colds. However, on September 28th (2009) I started to not feel right. I had ate lunch and felt a constant pressure in my chest afterwards. After a few hours however it went away for the most part. I went to bed and noticed that I couldn't quite catch a full breath no matter which position I placed myself in. This completely freaked me out and I believe I had a panic attack, and did not end up falling asleep until 6am. That night was also my first experience with a bought of yellow diarrhea. The next two days I experienced those same problems. I went to a walk in clinic and was told I had nothing more than heartburn. I was prescribed Ranitidine, and told to take gas relief pills and chew tums. During this time I also experienced SEVERE nasuea. It became so bad that just the smells of certain foods made me sick. However, I never threw up. I also could not eat much outside an occasional saltine cracker. Again I went to that same walk in clinic and was prescribed phenergan to help with my nasuea. This did help me eat a small amount of food but still I did not feel normal. I began to develop severe pains in abdomen. At this point I made an appointment with a doctor that practiced family medicine.
I've seen her twice and this is what she has been able to do for me:
-She took a blood test to check for diabetes, thyroid levels, bacteria in my stomach, anemia, etc. All came back negative.
-She took a stool sample to check for parasites, it came back negative.
-She also looked at a dime size bump I've had slightly above my tailbone for a few months now. She indicated that she thought it was a cyst.
-She prescribed me pantoprazole for GERD.
This process has taken almost a month! During this time I've experienced a crazy list of symptoms that seem to come and go at random intervals.
-pain in my lower back
-sharp pains in my chest, and abdomen (sometimes localized to my lower right back, or lower front left)  
-feeling that I need to burp but cannot
-yawning
-bad halitosis
-yellow stool with undigested food in it (this is the one symptom that has not changed) however, it does vary from diarrhea to loose thin
-nasuea
-fatigue
-erratic heartbeat

I've been told that stress can cause digestive problems, and I have been taking as many measures as possible to reduce my stress from school. However, it's hard to not feel stressed when I'm having all these problems with no answers. So please, if you have any suggestions what so ever, please offer them. I'm going to make another appointment with the doctor tomorrow and it would be great to suggest things to her or discuss any responses.