By Ryan Taylor Son Heung-min is set for further medical examination by Tottenham’s medical staff after sustaining a blow to the back in Thursday night’s dramatic 2-1 defeat to West Ham. The Spurs captain was substituted late in the second half and raised real concern when he was pictured writhing around in agony on the bench, supported by a number of Ange Postecoglou’s backroom staff. Son was the last Tottenham player to emerge from the home dressing room at around 11:30pm on Thursday night following the frustrating London derby setback which saw the hosts surrender a 1-0 half-time lead. Speak…