Pancreatic cancer or overreacting

I have been experiencing weird abdominal pains for over a month now and it is causing me so much anxiety. It has been a dull pain that has moved around, on and off, in my mid/upper abdomen over the last few weeks (5-6 weeks or so) I have felt the pain in the kidney areas too and originally the first episode was on my right side. Before this, I had experienced excessive burping on and off for months that would be bad on one day and be gone for a few and come back. Now I am at the point where the abdominal pain is more prominent in the upper center/left part and still is on and off, but I have also developed a dull back pain directly behind that. On top of the burping, I also have been passing more gas from the other end as well. I went to my GP and she thought it was my IBS that I have been diagnosed with years ago, but the symptoms I used toe experience were different than what I am experiencing now. She put the stethoscope to my gut and said she heard a lot of gas. She said normally you hear one or two sounds every minute, but she was hearing one or two every second. I mentioned that I was worried about other things like pancreatitis or pancreatic C so she ran some bloodwork testing all the normal stuff, and a few others like lipase and amylase (pancreatic enzymes) as well as a urinalysis. All was normal. The only abnormality was a glucose level of 112 which they used fasting as the reference time even though I had a full lunch the hour before so I assume that was a mistake and those levels were normal. Another thing I have noticed now is that every time I eat a meal, I get the burping more frequently. On the bright side, I have not experienced any weight loss, jaundice, nausea, appetite changes. In terms of digestive health, I have been passing smaller, thinner, infrequent bowel movements, but no color changes.

A little more background that may help, I was diagnosed a few months ago with GERD that was giving me a nasty cough every morning. I was given Prilosec to take before bed, and I take it occasionally after a big meal. Another thing is that I have always had horrible anxiety and at one point I had convinced myself that I had a brain tumor but after over a year of being miserable and experiencing many weird neurological symptoms, I had some sort of epiphany and realized it was all my anxiety playing tricks on my mind and body. I was also in the hospital once for a very bad and painful case of constipation.

I will be visiting my GP again for a follow up in 4 days. She advised me three days ago to try and eat more fiber, lay off the dairy (I am lactose intolerant, still eat dairy for years, but in moderation with no problems), and to use Miralax to loosen any possible blockages. I have been using it for three days, but have not passed a normal BM to my own normal standards. What other things should I ask her?

And I know I am very young (21) but I can't shake the thought that there is something more sinister going on inside me. Anyone have any similar stories or encouraging thoughts? Thanks!