Hi and thanks for the question,
the commonest cause of pain on the lower right side, accompanied by an infectious syndrome like fever, is appendicitis. In this case, acute appendicitis
must be excluded. Having an abdominal ultrasound, a good physical examination, complete blood count
in search of increased white blood cells and increased ESR and CrP levels shall be very suggestive of acute appendicitis.
Other causes of abdominal pain
in that region could include colics, gaz as you said, colonic tumours, crohn s disease, ulcerative colitis
acute sigmoiditis and many others.
However, it is critical to exclude an acute abdomen
especially due to appendicitis, do a complete blood count, CRP, ESR and a plain film of the abdomen to actually visualize the gas or not. A hemocult to detect blood min the stool or colonoscopy could also be done depending on the specialist s opinion.
I will suggest you take an appointment with a gastroenterologist or visceral surgeon for a complete evaluation.
Thanks as I hope this helps,