I recently recovered from Anal Fissure. Ever since the fissure, i have noticed that my Anus gets hard and swollen sometimes.  When i feel it with my finger, i feel like a hard bulge at the anus all-around the exit hole, like the exit hole gets swollen but about a few minutes later, it feels normal, without any bulge. I won't even be able to insert a finger during the bulge, the anus would be that tight. This is not painful or permanent, but only occurs occasionally. My anal sphincter also has become tight since the fissure. I feel this happens whenever i have acidity and feel my stomach is bloated. I have not been able to show this to a doctor as the bulge would not be present. Can you please let me know what exactly is this and why is it occurring?