Have him wear a condom. You should do that anyhow because while anal sex can be enjoyable ( there are lots of nerve endings around the anus) there are also some bacteria in the anal canal that you really don't want to expose him -or you - to getting. The condom will keep any residual feces off of him. Make sure they are well lubricated, however, because the tissues inside the anus are delicate- just like the tissue inside the vagina. You don't want to tear these tissues at all because then they provide an opening into the blood stream for infections, bacteria etc-some of which are very dangerous. The lubricated condom makes this unlikely to happen and if it does it protects him from infection. Do be careful to protect yourself by having intercourse in a comfortable, well lubricated way so that you do not cause any bleeding.
Make sure as well, that the penis does not re enter your vagina when you have had anal intercourse. If you want to have vaginal intercourse afterwards-- get a new condom that has not waste material on it, and make sure your hands and his hands are clean and washed after touching the anus. You want to keep these two areas very separate so you don't cause a vaginal infection or a systemic infection (involving your whole body).
I'm not a doctor but i did have a friend who asled me about this and i did a lil research, one thing you could do is a self enema to clean out the insides of your yaa..., thats one idea