Manhar, I know you said you were at a sports injury clinic but did the therapist think your 'flat feet' were associated with your injury, or just the fact you have flat feet. I work with children which is quite different from adults but I would not treat asymptomatic flat feet i.e. not causing any problems (as I said, this is the general approach for children, but not wholly sure about adults).

onwards and upwards

Gaz