Chronic Right-Side Abdominal/Back Gallbladder Pain

A quick little medical history about myself: I have had IBS for years and have been able to manage it well. I am lactose intolerant, with certain dairy products affecting me worse than others. And I have been seen by an ENT for a chronic GERD related cough for which I was prescribed Prilosec.
For the last two months, I have been feeling an abdominal pain that has moved around as it progressed. Even before this, I have noticed that I have been burping quite a lot. It first started in episodes that would come for a few days then go away and come back a few days later. The first episode was on the right side near my appendix but then went away on its own after a few days. Then it came back on the other side and another time it was more in the back near my kidneys. Now it is becoming more frequent and is accompanied by occasional back pain. All of the pains are relatively mild but are becoming more frequent now. I have been burping a lot more now and it typically gets worse after a meal. The pain now is predominantly in my upper center/left abdomen. I went to my GP about five days ago, and she put the stethoscope up to my gut and said she heard A LOT of gas in there. I also have not passed a normally sized bowel movement in well over a week. They have been infrequent and smaller than normal, very thin, but normal colored. I have taken Miralax once a day for five days now but still have not passed a normal bowel movement, just smaller infrequent ones. Anyways, she ran some blood work and urinalysis on me to check kidney, liver, and pancreatic functions. Everything came back normal (somewhat of a relief) and I have a follow up with her in two days. Since my last visit, I have tried to limit my dairy intake, and well as my carb intake, such as breads and such. I have also been eating more fiber-rich foods and nothing has changed, in fact, things have been getting worse since my last visit. The back pain now comes instantly when I get up in the morning but fades over the day. And the GI symptoms flare up after I eat anything, especially the excessive burping. I've still been eating the same amount of food and my weight has stayed the same, but these symptoms are not only uncomfortable, but they are causing me such much unwanted stress and anxiety.

Does anyone have any similar stories? Can anyone share any ideas as to what might be going on or what I should ask my GP in two days?
Thanks!