Upper left abdominal pain with odd variety of symptoms

Hello everyone, I'am a 21 year old male and have been experiencing upper left abdominal pain right under my say, 8th rib towards my left side for about 3 months now. It's usually on and off but more on. There are also other symptoms such as nausea, aching in central upper abdomen, and rare chest pain. I'll get bad pressure and gas pain after drinking anything with carbonated water, or possibly with b12/acidic. I had been to the ER before I got the abdominal pains because I was having chest pain prior. They said it was either a muscle or GI related. A month later, the abdominal feelings came on and as of yet have not gone away for good. at first the discomfort got better with back pressure, now it usually just gets better with position(sitting, standing). After eating I feel fine and a majority of the time it seems to go away late at night. I did go back to the ER and they found nothing wrong with me, they did a CT, Xray, bloodwork, no dice. After the tests, the doc said it could be IBS, however I have yet to be constipated or have diarrhea, though my stools have been light colored most of the time. Also there is a lump/swelling on my right side, where a muscle/tendon? joins the bottom of the ribcage. So any ideas? I know its hard to diagnose things online so I've tried to be as descriptive as possible. et me know if anyone needs more info, I really appreciate your time for reading this!