Hi. Thanks for your query. Noted your history of brown colored stain on underwear and probably the presence of feces, happening again. The possibilities are that yo have sticky stools or suffering from conditions like descending perineal syndrome or colitis or leakage problems may be due to farting or so. Another possibility is local skin conditions like dermatitis, excessive sweating and so on. To get a correct diagnosis and proper treatment you need to do the following: Get a consultation of a General Surgeon for clinical evaluation, examination and tests of blood, urine and stool, ultrasonography of the abdomen, per-rectal examination, colonoscopy and biopsy. This will give the proper diagnosis which is so much important to have a proper line of management.