I've experienced the following symptoms for the past three and a half months:

- queasiness/nausea beginning shortly after eating which lasts 1 to 3 hours (no vomiting, though, and the nausea is not severe but definitely present). This is probably the symptom that bothers me the most because it distracts me from my work and makes me generally feel uncomfortable. For the first two months after my symptoms began, I didn't eat very well because of this nausea and as a result lost about 10 lbs. unintentionally. Not sure if I've gained back any as I haven't weighed myself in a while, but I often do have to make myself eat.   

- feeling full prematurely when eating a full-sized meal. As a result, I've been eating much smaller portions and snack throughout the day instead of eating big meals in one sitting. This goes along with the nausea and causes me to not have an appetite a lot of times.

- mild bloating after eating and sometimes in the morning; this is more of a sensation of bloating rather than being physically bloated - my abdomen is not distended, etc.

- chest tightness / feeling like I'm not able to draw a full breath. This happened during the first two months or so, but it has subsided some.

- occasional constipation which usually resolves after a few days. Bowel movements are generally regular and not a problem.

- some lower back pain and a stitching kind of pain in left upper abdomen

- excessive burping in the morning and after eating; by excessive I mean noticeably more than I used to before this all started. Along with this, lots of gurgling sounds from stomach and abdomen area even when I'm not hungry.  

- finally, I began experiencing these symptoms after a bout in mid-February of pretty intense abdominal pain that came in waves along with diarrhea, which would relieve the pain somewhat. I'm pretty sure this was not any kind of food poisoning or stomach flu, because there was no vomiting or fever, and I had not eaten anything questionable beforehand. After that episode was when all these other symptoms started..

I went to the doctor's twice soon after these symptoms, and she prescribed me omeprazole because I mentioned that I had a little bit of heartburn. The omeprazole didn't make any noticeable difference to me, so I went to a GI specialist in late March. He suspected either H. Pylori or gastroparesis. Eventually got an upper endoscopy done which turned up nothing, and the biopsy was negative for H. Pylori. I should also mention that I also got a blood and urine test, both of which turned up nothing as well. Since I don't think the acid reflux meds help any, currently I'm taking probiotics and some traditional Chinese medicine, which seemed to help for the past two months - I've started to eat better and more regularly and felt okay mostly again, BUT this past week I had another bout of intense abdominal pain + diarrhea similar to the one back in February, and now I'm experiencing the same nausea/lack of appetite/bloating as before. I'm all out of ideas as to what this could be, and why it would last so long.

A few details about me: age 22, female, was generally in good health before all this, though I had experienced quite a bit of stress and anxiety for about five months before initial symptoms began. But now I'm not really stressed out about anything and this is still happening... help?

Other things I'v considered: gallbladder issue (symptoms don't really fit, though), maybe gastroparesis, IBS? Any help would be greatly appreciated! And apologies for the wall of text!