Hi, Welcome to Health care magic forum. As you describe, it appears that there is involvement of two systems. 1)There is infection of the sinuses, from the maxillary to the occipital sinuses, causing pain allover the left side of the face. 2)The other is the gastric pain, causing the referred pain to the shoulder, and arm. The other causes may be the pancreatitis, or splenic swelling.The other may be the urinary tract infection. I advise you to consult a surgeon for diagnosis and treatment . You may need to have M.R.I. for confirmation of the disease. Wishing for a quick and complete recovery. Thank you.