3 year old child keeps crying in sleep?

It's 3:30 in the morning and I am sitting here in tears. I am listening to my 3 year old cry every 5 mins in her sleep. She doesn't have a fever. She has autisum and doesn't talk yet so she can't tell me what's wrong. I am trying to figure out what's wrong. Lately she has been really chewing on things and putting things in her mouth. My husband says she will probably be sick cause this morning she put the scrub brush for dishes in her mouth. I am worried it's something else. Could she have cavities? She refuses to let me look into her mouth. She is strong and she fights and bites. I want to take her to the dentist but the insurance company has the family with one who doesn't accept patients younger than four. I am so worried that she does. I brush her teeth everyday. Like I said there is no fever so I am pretty sure she is not sick. She is not acting like she did a few weeks ago when she had tonsilitis and than an ear infection. I feel like the worse mother on earth cause I can't figure out what could be wrong.