Hi...
You need to get an X-ray of the foot done in Ap, Oblique and Lateral views...
I am guessing that your child is an active child? As in interested in sports?
It could be Iselin protrusion... Its harmless and can be managed with proper soft footwear and rest and ice packs if slightly red or painful...
Thank you.
Dr. Arshi Raunaq Singh
M.S. Orthopaedics
Apollo Hospital - Jubilee Hills, Hyderabad
Next Steps
Get the x rays done.
Show local orthopaedic surgeon... Will asses the lateral compartment of leg.
Health Tips
Rest is needed for some time. And can restart sports or play after a couple of weeks.