G.H.
Dear A. B,
I would scare the heck out of her and tell her to either fess up what she has done. Tell her 2 things. 1 I will call her parents 2. I will call the police and file a police report if she does not come clean. If your son says she goes in your room that's enough evidence that she has done something wrong.
I had a babysitter steal from me who my kid loved. She took a few necklaces of my mother's but the fact I had no proof of the jewelry she took I did not press charges against her. I confornted her and she said she purchased them years ago. I told her she was lieing to me. She moved out and we never heard from her again.
Do you have her parents name and phone #? If you do I would call them. How old is the sitter?
Let her know your son has stated she has been in your room.
Keepme posted.
G. H.