Pain in the shoulder after pancreas surgery?

I had surgery last tuesday on my pancreas. They removed the tail due to cysts that were there. I didnt have pancreatitis. Starting today i have a sharp pain in my shoulder. It hurts more than the surgery site. Any ideas? What could be causing this pain? I have no other symptoms except a slight case of drymouth i think might be related to the oxycodone they gave me. The pills do not help with this pain.