Understanding New and Severe Abdominal Pain

Since you are a man, appendicitis is the most likely cause of pain in the right lower abdomen along with fever. Seek an urgent evaluation by your doctor.

Appendicitis is the most dangerous cause of a fever and right-sided lower abdominal pain, but other causes may be considered.

Inflammatory bowel disease (such as "Crohn's disease") can cause inflammation in an area of bowel that is close to the appendix, and it can also result in a fever.

An abscess can occur anywhere in the abdomen. An abscess could also explain your symptoms.

Your symptoms could also come from "colitis," an infection or inflammation of the colon.

One common cause of colitis is an infection that can develop following antibiotic treatment. Infections from contaminated food, such as salmonella, shigella, or campylobacter can cause similar symptoms.