That's a tough one, especially since there are some important details left out. With anal sex, it's very, very important to start out slow, gradually stretching the sphincter muscles with increasingly larger toys (or fingers), working up to something penis-size. Of course using plenty of lube is also necessary. But details such as the size (diameter & length) of the object/penis being inserted, how rough you are, how long your session lasts, how often you do it, etc. All these things would factor into your overall anal health.
Without knowing anything more, I'm speculating that you are maybe being a bit too rough, or are having anal sex too often or for too long. There should only be trace amounts of fecal matter in your rectum, so there shouldn't be any 'compression' taking place. I'd say it's more to do with muscle trauma.
I would avoid medications to solve this issue if possible. Instead I would try to change the anal sex routine. If you have sex long & hard, try going more gentle, and maybe for not as long. If you are using very large objects, try something smaller instead. If you aren't warming up properly, or aren't using enough lube, well, you get the picture.
If you have any more details to share, it may help us to better help you through this issue.
And by the way, it's great having more anal sex lovers here!