(EDIT: Since I posted this message, the picture has been removed)
I honestly don't know what that is a picture of, but I'm pretty sure it's not permitted on this site (someone correct me if I'm wrong). There are younger people who use this site, along with squeamish people who don't expect to see these sorts of things.
I will attempt to answer your question. I've had anal sex before, and I haven't had any problems. Rigourous anal sex can damage the insides of your rectal walls. They're very sensitive and if you're not really, really careful, you can damage yourself. It takes a long time for them to heal, and if you're constipated or are undergoing repeated rectal irritation, it can take get infected. Take it easy with the sex, and, most importantly, take a mild stool softener to make it easier for your body to heal. I sincerely hope you and the person you're sleeping with were using condoms. Lack of condoms can greatly complicate and jeopardise your health.
I would also strongly suggest going to a doctor, especially if you're experiencing pain or discomfort of any kind.
If you have any more questions, feel free to Private Message me.