Colonoscopies are great. You won't feel a thing and for about 45 minutes after you wake up you'll have the best buzz you ever had in your life.
This. Jack is 100% right, these days its almost a pleasure!
Seriously though, go and see a colorectal specialist immediately. I had an anal fistula once, it was awful and took over a year to heal after surgery.
Not kidding, if you catch stuff early you can fix it, let it fester and the outcomes can be disastrous.
Do not just trust a regular doctor. Insist on a referral to a colorectal specialist.
Don't delay.