please do stool exams and proctoscopy from doctor
Look into Pilonidal Cysts as a possible cause. Keep clean with alcohol. It can be surgically removed. Not fun.
Pilonidal Disease Causes, Symptoms and Treatment
What is pilonidal disease? Pilonidal (say "py-luh-NY-dul") disease is a chronic skin infection in the crease between the buttocks. People with this condition have one or more cysts in that area that tend to get inflamed and infected. A pilonidal cyst may look like a small dimple (called a "pit" or "sinus"). Hair may stick out from it. See a picture of a pilonidal cyst . What causes a pilonidal cyst? www.everydayhealth.com