Thank you for asking your query.
Form your question I understand that you are having a rather troubling pain in the lower left rib cage and back.
There are many possibilities for this pain but the ones I would like to consider are the following :
1. Musculoskeletal pain at ribs and intercostal muscles
2. Lung/ Pleural irritation
3. Diaphragmatic irritation
4. A splenic involvement
5. Peptic Ulcer
6. A pancreatic involvement.
7. A spine problem, with pain radiating
Now there is no need for any alarm. The way we go about finding the cause is a step by step approach and to rule out most common and not to miss causes. For that you will need to get few tests done with the help of your Physician. This will be a Chest XRay, XRay of spine – AP and Later , a Ultrasound of Abdomen, Complete Cholesterol study, S. Amylase, S. Lipase. This will rule out many possibilities and if needed further tests can be done. I am sure you many options for pain relief. Now I would recommend you to use an anti Ulcer drug (Pantoprazol / Omeprazole ) in consultation with your Physician. This has to be taken just before sleep. If the pain has an ulcer component in it, this will help.
Hope this helps.
Please feel free to ask any follow-up questions.