Mesentery is the attachment to the gut that holds it suspended inside the abdomen.There are lymph nodes within it which collect nutrients from gut after digestion of food.Sometimes they get infected and become a source of pain.As mesentery is a long structure and hangs with certain degree of mobility the location of pain keeps on changing with the position the patient adopts.
This can be differentiated from appendicitis with it's characteristic pain pattern and an ultrasound may demonstrate a healthy appendix.Sometimes it is hard to differentiate it from appendicitis in spite of all available investigations. In case of doubt a laparoscopy will be able to differentiate it from appendicitis.If still in doubt an appendicectomy is done which many times cures it.It just like two in one treatment.If correctly diagnosed a simple conservative approach by the way of parenteral feeding ,antibiotics and analgesics will cure the condition .