Severe Upper Abdominal and Back Pain- Gallbladder or Pancreatitis?

[Amp180]

Over the past 5 years or so I’ve had sudden flare ups where my upper abdomen (below breast bone) hurts terribly and my back (between my shoulder blades/thoracic region) hurts. The flare ups range in duration from 1-2 hours to 24 hours. Post flare up the residual (slightly reduced pain) lingers. The back pain and tightness has been off and on constant for the past year. My GI has done elimination diets, ruled out CIBO, and ruled out ulcer. Hypothesis is GERD but I don’t believe this is the right diagnosis. I don’t have pain or burning in my throat or esophagus. I also take Omeprazole 2x daily. I’m a 30 year old female 122lbs and eat rather healthy and not overly fatty foods. I need to get blood work done to check the enzyme levels and ultrasound of gallbladder. Any guidance or thoughts on what this could be would be very helpful. Thanks!