Has this ever happened to you

So me and my SO were having sex and we always use to try anal but it was only one time that i remember it actual went in and it felt so good but that was back a few months ago now recently every time we try it hurts and I’m sure half the time I’m not as relaxed but most time I am and it still hurts but yesterday it hurt so bad trying to give it a shot again and now today my anal feels like it as a small blister or something Idk what to do 😢🤦🏾‍♀️