Sharon, hugs on your situation with a beloved and aging dog. I know little about Maltese per se, but have had some aging dogs in my time. I think your girl gets in the bedroom, without you, and gets lost. With her eyes and ears going dim on her, she may be left with scent and floor vibrations. IF you are in a room with her or very nearby, she could locate your direction and get to you. Without you that close, she is in a terrible confusing maze perhaps. I don't think there is a solution, except loving patience. And crating her when you are going to outside the house for any length of time without her.