Hello from JustAnswer.
If you tried to attach a picture, it did not come through, but the is much that I can say from your description.
This would be most likely due to a hemorrhoid or an anal fissure, which are conditions that are worth treating, but there is no reason to be frightened.
A hemorrhoid is a distended vein that can occur inside or outside the anus. An anal fissure is a superficial tear of the lining of the anus. The mucus is typically a sign of inflammation, and the inflammation also can cause the itching, bleeding, and discomfort. The inflammation also can cause swelling, which can cause the difficulty in going to the bathroom. Either a hemorrhoid or an anal fissure can get significant inflammation, so the problems cannot be differentiated based solely on the symptoms.
It is important to note that constipation can make these problems worse, so part of the treatment is also oriented towards easing the constipation and softening the stool.
There are a number of home interventions that can help with this problem. There are a number of anal medicines that are mostly marketed for hemorrhoids, but will also help with anal fissures. In particular, it will would be reasonable to use one that has hydrocortisone to help ease the inflammation. It also is appropriate to increase fiber intake to help ease the constipation. This can be done by increasing the fiber in the diet or a fiber laxative. It also would be appropriate to take a stool softener, such as Colace/docusate.
If these home interventions ease the symptoms, then no further evaluation or treatment is necessary, but if the symptoms persist, it would be appropriate to see your doctor.
Is there any other information that would be helpful?
In addition, if you would like for me to review the picture, I would be glad to do so.