I would come up with three possibilities, these include:  The first possibility is of Peptic ulcer disease or Hiatal hernia. Diagnosis can be confirmed by upper GI endoscopy. Try raising the head of your bed about four inches with blocks. The second possibility is of pancreatitis as it may cause upper left abdominal pain which is worse when bending over or sitting. Pancreatic enzymes like serum amylase and lipase should be measured to rule out any pancreatic cause.  The last possibility is of any kidney stones which may present as such sharp pain radiating to the back. For this purpose you need to get an ultrasound abdomen and kidneys done.  I suggest you to consult a physician and get an ultrasound upper left abdomen, pancreatic enzymes, upper GI endoscopy to rule out any peptic ulcers and a chest x-ray done.  Hope this answers your question. If you have additional questions or follow up questions then please do not hesitate in writing to us. I will be happy to answer your questions.