I like what everyone said. The most important thing out of everything said is to let her know you believe her. She needs your support. When it happens hug her and ask her what she sees (male/female) raise your hand for agreement of height. dark/light, happy/sad, disable? Emphasis on leg/arm.Then protect her. Whether it be with the suggestion of a toy that will help her or you using your spirituality to have her see you in prayer, mediation or gentle, gentle confrontation to the Spirit. (DO not be loud and harsh. That will be the worst thing to do). Instead say, "You are scaring her. Please do not show yourself to her. She cannot handle it." Something like that. The idea is to help the spirit to know they are not welcomed and that you are standing up for her.
My Son would wake up and say, last night I saw that crazy old lady again. She would traumatize him at night. He said he has seen her once every year for the last three years. (That he could remember). That week she had been there twice and once in the car when he was 4 he is now 7. I had no idea. He made mention once but I thought it was a nightmare. It's when he is about to sleep. He said she is old and ugly. she even hits him, grabs and pushes him. He said he cannot speak, which makes me think she is one of those witches who they say hold you down in your sleep. (My son says he is awake. Anyway, I was angry. My husband said it was a dream when she came one night and made a joke of it. I let him know I believed him and Every night for a week I prayed and asked God to never let her enter the house or follow him. That she was not welcomed ever again. To put angels for us at all exits and entrances of the house for now on (Hebrews 1:14). I took it very serious. Then my son needed to be empowered and he said his own prayer. I told her not to come back and I remembered something in a book or a t.v. show, I asked her to go to God. Not sure if you should do that part. It felt right for me so I said it. It has been 6 months and he is doing better. He is still afraid she will come every year of his birthday. I will renew the prayers often.
I hope this helps. Your spirituality is your empowerment. If it gets worst please find a more professional help, to which I am not sure but I will be praying for you myself.