<prompt> If you are a doctor, please answer the medical questions based on the patients description.Hey doc,21 yo male with lower right abdominal painpressure approximately 4-5 months. It is not aggravated by diet. The only other symptom is it is worse sitting. There are no abnormal bowel movements. No nausea or anything. Sometimes in radiates to the back. Pain has been consistent for 4 months no improvement or worsening. Any ideas would be GREATLY appreciated?Thank you  <response>: Hi. Thanks for your history and query. The possible cause of such a pain in the right lower abdomen, which worsens on sitting down and refers to back and is present for 5 months can be due to::Iliopsoas abscessTuberculosis of the abdomen. I would advise you the following:First we have to investigate you thoroughly. Investigations:Routine blood investigations like Complete blood picture, blood sugar, urea, creatinine, liver function tests, thyroid function tests.Urine -routine and microscopyStool: routine, microscopy, occult blood, culture and sensitivity.Ultrasonography of abdomen, Colonoscopy All these investigations should be within normal limits for one to say you have IBS. Once a proper diagnosis is made it is easy to chart out the treatment. 