That smell is probably a lodged fecal plug somewhere North of your stretched out sphincter muscle. Try pooping with your feet resting on a few phone books, apparently this technique provides for a more robust and memorable experience. Good luck, hope it's a clean break :)
It wouldn't be gonorrhea after 10 years. Maybe you have some hemmorhoids or something internally.
Its almost shocking that you gave up anal sex for 10 years instead of just getting it checked. I doubt it is gonorrhea, but seriously - that's easily cured.
If you've never been tested for stds, you really should be.
Aj