Could radiesse (dermal fillers) harden in the face and cause pain?

Check for infection. Have your MD check injected areas for infection.
Harden yes pain no. I have seen the product harden in someone who had a photofacial the day after injection pain however is different. Unless you were injected today the pain should not be present . It could be an infection the area my feel warm to touch and be very tender. In any event go back to that doctor and make sure everything is okay.