Skateboard heels crystal

Who should i consult about sore knee? - sore knee sympathy card

I had probs with my knee for a long time have several tapes, supplements, various buses, etc., etc., trying
Someone suggested that he flat feet - had good friends! and may need to use templates.
Who would be the best person to ask about him? Osteopath? Chiropractor? physio? chiroptist?

I do lots of sports, I'm not on weight and I am in quarantine.