I would suggest that you see your doctor for an examination. You may have a lower GI infection. Besides an examination, the doctor may want to send a stool sample to be cultured.
Infections in the lower large intestine, near the rectum, are not uncommon and usually not serious, but when they are causing distress (such as 5 days of difficulty sleeping) it needs to be diagnosed and treated with prescription medication.
It is also possible that other causes could be involved including various inflammatory bowel diseases. Only your doctor can determine if anything else is present. Regardless of the diagnosis, there is help available to relive your symptoms.
Yes, IBS can certainly cause this.
Irritable Bowel Syndrome (or IBS) most frequently presents with pain/pressure/discomfort in the abdomen/stomach that is often relieved only after having a bowel movement and with frequent diarrhea, constipation, or both.
Additional symptoms of IBS can include mucus in the stool, swelling/bloating in the abdomen/stomach, and frequently feeling like you have to have a bowel movement even if you just had one.
Dietary changes, relaxation techniques, and sometimes medications are used to treat IBS.