Hello...i think ur kid has scratched his conjnunctiva....nothing to worry...it will heal on its own

By eye sclera I expect that you mean the visible white portion of the eye. Mild congestion on that part may heal without any medications most of the times. But it can also lead to infection sometimes. Continue to observe the eye closely for the next few days. If it is getting worse, get an ophthalmologist consultation. Otherwise, consider yourself lucky !