If parathyroids don't "work", typically, they are removed, in order to prevent problems. Possibly, one or both of them "does" work, at least, intermittently in order to raise your levels that high? This does seem to be a parthyroid issue.
I supposedly have two parathyroids left but they haven't worked since my thyroid operation. I am typically hypocalcemic (meaning low calcium levels).
You're worried about what, happening again?
High blood calcium often indicates that too much calcium is being pulled from your bones. This is usually caused by a parathyroid malfunction or tumor. If it's known that you have parathyroid issues, why haven't the offending parathyroids been removed?