HI welcome to health care magic.........
both are almost the same , sigmoidoscopy is first step and if found negative can go for colonoscopy.Constipation
itself can cause trauma and can explain the pain.
U can get a sigmoidoscopy and then if its normal study then go for a colonoscopy. If abnormal on sigmoidoscopy no need of colonoscopy.
Once if both are normal then can get a complete stool examination , and if everything is normal then go for managemant of constipation.
Step 1 - dietary management - pleanty of fluids , fruits and vegetables.
Avoid choclates , spicy foods and fatty fried foods.
Step 2 - use laxatives like lactulose