My 10yo had sudden onset of pain while running around at school playtime around base of big toe - have rested/ice/physio but no relief after 5 weeks?

Check growth plate.: Quite possibly there has been a disruption or fracture of the growth plate in the big toe. X- rays may help with the verification, but not always. At any rate, the area must be protected from further injury. One the damage is healed, then physio is appropriate. Initial ice application is used to reduce pain and swelling, but continued application may reduce the healing. Perhaps, second opinion.