I just had my gallbladder out 5 weeks ago.i have had pain iin my mid to upper back.what can it be?

Hard to tell: Without an examination. It could be normal recovery with muscle spasm discomforts in the back. If it were serious like pancreatitis it would usually be severe pain with nausea & vomiting. See your surgeon if there is worsening pains, vomiting, bad nausea, associated abdominal pain, or if the back discomfort does not resolve.

? Retained Stone ?: There are many possible explanations for your back pain, from simple musculoskeletal pain to the possibility of a stone in your common bile duct. Please return to see your surgeon so that (s)he can take a more complete history, examine you, and order the appropriate tests to get you well.