I suspect that its a hemorrhoid. A hemorrhoid is an enlarged blood vessel in or just outside the anus.
To reduce the swelling and ease discomfort, you want to keep stools soft by taking fiber and drinking plenty of liquid.
You can get bulk-forming fiber powder (psyllium fiber) without a prescription. There are many brands. Generic versions work just as well as brand name products. You can find flavored and sweetened types. The usual dose is 2 teaspoons or 2 packets in liquid once or twice a day.
Unprocessed bran is an alternative way to take fiber. It may be cheaper than psyllium fiber. But it might be less convenient to take. You can buy it from health food stores and some grocery stores. (Look for "Quaker Unprocessed Bran".) Take 1/4 to 1/3 cup per day. Mix it with yogurt, cereal, applesauce or anything you like.
Bran and psyllium fiber are not laxatives. They are from natural, nondigestible seed husks. They stay in the intestine and absorb water to make the stools soft. They make bowel movements bulky and soft. So its easier for your intestine to handle.
Some people notice a little cramping, bloating, or gas when they begin taking fiber. If so, start with a small amount and gradually increase the dose. Keep increasing the dose until your stools are quite soft, like paste. Drink plenty of liquids with it.
Do not sit on the toilet for long periods. This tends to make hemorrhoids push out and swell up.