MY SON IS 11 YRS OLD. HE RECENTLY HAD FLU , NOT MORE THAN A WEEK AGO. IN THE MEANTIME HIS YOUNGER BROTHER HAD CHICHEN POCKS. TODAY, IS THURSDAY, AND HE IS COMPLAINING ABOUT HIS NECK, THAT IS SORE . HE EXERCISED RUGBY TODAY, AS WELL. COULD IT BE FROM THE RUGBY OR COULD THE CHICKEN POCKS, HAVE ANYTHING TO DO WITH IT?????