Hello and welcome to HCM.
It seems that the child has a condition called as stasis
dermatitis caused due to some form of
venous insufficiency in legs.
If I were your treating doctor ,I would recommend,
-Advice investigation like basic haemogram,blood coagulation factors and Doppler scan for blood circulation of legs.
Further medications will depend upon diagnosis.
-Apply locally topical corticosteroid ointment like
triamcinolone 0.1% ointment (physician's prescription drug)
-keep skin moisturized by applying vaseline
-avoid standing for long at one place
-do frequent ankle exercises like flexion ,extension and circular movements at ankles.
-applying compression bandage in morning,sitting or sleeping with leg elevated
-keeping a watch over symptoms like
shortness of breath,
chest pain,sudden cough and report immediately to paediatrician/ER.
Thanks and regards.