Thank you for the input.
Appendicolith is a deposit in appendix which has got calcified or like a stone.
This can appear opaque on X ray.
Sometimes, it is associated with appendicitis
but it is not specific for diagnosis of appendicitis which is rare in infants.
In other cases it can be an incidental finding.
Sometimes, an ingested foreign body or artifact can be confused with appendicolith.
As the ultrasound could not detect any sign of appendicitis or enlarged appendix, it is not worrying.
You need to observe only. Constipation can also cause pain.
If the pain gets worse or continues, you need to take a review by doctor.
If you have any query, please feel free to ask & continue conversation by using reply button.
This will help me to explain further & satisfy you.
Wish his healthy life.