Sitting on the toilet, use the syringe with warm water and inject the water slowly, then evacuate. Do this a times and everything should be good for a few hours. And if you're comfortable with your body, as anal probably are since you seem pretty sexually adventurous, insert your finger to see if you are clean inside.
How can I avoid pooping during anal sex? - GirlsAskGuys
You are wanting to and out the rectum, not the entire colon with a large volume enema. And remember that if pooping play with fire you will get burned on occasion. Especially since you are practicing safer sex by using condoms, this shouldn't cause too much trouble. Relax and enjoy your sexuality!
How can I avoid pooping during anal sex?
What do you expect? That hole was not intended for sexual sex. It was made to hold and then release poop. If you insist on doing that very gross by the waythen you might consider an enema first to evacuate your rectum.