I can understand your apprehensions. The mesenteric masses can be benign or non cancerous and can even be cancerous. Benign tumors can be cystic lymphangiomas, desmoids tumors, lipomas, or Whipple Disease. Malignant tumors include lymphomas, sarcomas, gastrointestinal stromal tumors (GIST) etc.
Usually CT with contrast is enough to reach a diagnosis. Usually pain with diarrhea can be due to IBS, Crohn’s, celiac disease, food intolerance etc. So, you could be having a benign tumor as well. I am sorry, but nothing much can be said unless the CT is performed. Let’s hope for the best! Take care!
The medical advice given should not be considered a substitute for medical care provided by a doctor who can examine you. The advice may not be completely correct for you as the doctor cannot examine you and does not know your complete medical history. Hence this reply to your post should only be considered as a guiding line and you must consult your doctor at the earliest for your medical problem.