Welcome to the MedHelp forum!
There are a few things which come to my mind. May be there is a bleeding in your gastrointestinal tract, say from an ulcer. Anemia could be due to poor intake, loss from body as happens in acidity and GERD, rectal polyps (ruled out in your case) etc, due to improper absorption or due to storage disorders. Also you need to get a pheripheral blood smear done to know the RBC count, structure and whether there is cytopenia (general decrease in cell count). The renal function and liver function needs to be checked as also electrophoresis of hemoglobin to know whether there is thalasemia trait or sickle cell anemia. You should get your stool examined for occult blood.
Middle back pain could be due to a bleeding stomach ulcer or due to spinal nerve compression.
Hope this helps. Please let me know if there is any thing else and do keep me posted. Take care!
The Content on this Site is presented in a summary fashion, and is intended to be used for educational and entertainment purposes only. It is not intended to be and should not be interpreted as medical advice or a diagnosis of any health or fitness problem, condition or disease; or a recommendation for a specific test, doctor, care provider, procedure, treatment plan, product, or course of action. MedHelp is not a medical or healthcare provider and your use of this Site does not create a doctor / patient relationship. We disclaim all responsibility for the professional qualifications and licensing of, and services provided by, any physician or other health providers posting on or otherwise referred to on this Site and/or any Third Party Site. Never disregard the medical advice of your physician or health professional, or delay in seeking such advice, because of something you read on this Site. We offer this Site AS IS and without any warranties. By using this Site you agree to the following Terms and Conditions. If you think you may have a medical emergency, call your physician or 911 immediately.