My Husband Has Metal Plates In His Head From Severe

My husband has metal plates in his head from severe head trauma after being hit with a baseball bat. He had them put in when his skull was basically destroyed. He has severe pain which triggers seizures that have caused him to go into cardiac arrest. After feeling his head tonight it seems like they have moved and there's a soft squishy spot on the back of his head and he is in severe pain. What can be causing this?