Here is one possibility I found doing research using your symptoms.
Mesenteric adenitis is a self-limited inflammatory process that affects the mesenteric lymph nodes in the right lower quadrant. Its clinical presentation mimics that of acute appendicitis. Until recently, the diagnosis was most frequently made when laparotomy performed to assess presumed appendicitis yielded negative findings; now, cross-sectional imaging is routinely applied in the examination of patients.
Mesenteric adenitis is usually a self-limited disease, and management is conservative. Radiologic intervention is generally not indicated. Rotavirus and other viral vectors are the presumed cause in most cases. Although cultures are seldom obtained, most cases resolve without antibiotic treatment.
Infections cause our 'glands' to swell - you might have noticed this from time to time in your neck when you have had a sore throat or sore ear.
The commonest lymph glands to swell in this way are in the neck, under the arms, and in the groin. It's easy to spot these because they get sore and swollen.
However, there are similar glands inside the abdomen around the blood supply to your gut - in what is called the 'mesentery'. When these glands swell to fight a virus, or other infection, they get sore but you can't see the swelling.
All the patient is aware of is tummy pain and feeling a bit fevered. To doctors it can look exactly like appendicitis and it is only clear that this is not the case once the surgeon does an operation and finds the appendix to be perfectly healthy.
So, with 'mesenteric adenitis', which settles all by itself, it is a matter of waiting until it goes away, but being careful to exclude appendicitis.
I hope this helps, please let me know if I can do more detailed research for you.