What do you think is the problem? What action should I take? I have a discomfort, kind of painful, feeling in my rectum. Almost feels like I am constipated, but I had a bowl movement, though not a very substantial one.

Very concerning for. Something in your rectum, that occupies space and is interpreted by the brain as stool but may be swollen internal hemorrhoids or a tumor, benign or malignant. Please at least get a digital rectal exam from pcp or see a colorectal or GI doctor soon.
You . You could be dealing with a hemorrhoid, polyp, or even cancer. My advice is to see your primary care provider for an evaluation. If you are a female and have had vaginal deliveries or a young person it is likely a hemorrhoid. Best of luck.