What Causes Pain In Arm Which Has Metal Plate In It?

Hello, I have metal plate on my ulna bone for over 3 years now, and a week ago i started to feel sharp pain that comes and goes. I can use the arm normally but suddenly it just starts hurting. What can be the reason? I am 22 years old, broke my right arm (both radial and ulna) 5 years ago and had 3 surgeries on it. I didn't have any problem until these pains that stared a week ago.