What Causes Pain In Back And Armpit On Stretching After Undergoing Bowel Resection?

Hi, 6 days ago I underwent a bowel resection due to Crohn s disease. Although I m healing well and am up and moving around, I have a horrible skin pain on the back of my armpit. When I stretch it feels as though the skin is stretching and tearing.During my surgery I chose to have an epidural, which unfortunately didn t work. I read somewhere spine damage could be a cause of this?Also I m having an awful lot of bowel movements throughout the day, meaning I m more than likely not getting all the nutrient and vitamins I need, with the crohns I struggle to eat foods with b12 in them? Is this the problem?