In my opinion ten days is inadequate time for keeping the hand in plaster if there was a hairline fracture. I would like to have kept the plaster for 3 weeks and then clinical check for pain and tenderness along with X-ray at that time.
Seek an orthopedic opinion and reassess with fresh X-ray
Next Steps
You can continue to apply ice over the area
Health Tips
Avoid any strenuous activities with the injured hand