Hello. Welcome to hcm
As your doctor has cleared by your doctor,only thing now left is either ligament sprain
or muscle pull. Generally children dont need pain killers as they recover soon. My advice is,try not to put too much weight like trying to make child walk when pain is there. Bruise
cannot make so much pain. Dont put oils or massage
the area. Have a follow up later with in a week.
All the best