<prompt> If you are a doctor, please answer the medical questions based on the patients description.MY 7yr old daughter has been moving her mouth constantly, opening and closing her mouth as well as stretching her upper lip up and down. I checked her mouth and she has a sore on her inner cheek, perhaps a canchor sore. I also think she bites her cheeks when she sleeps.  <response>: Hi. Thanks for the query. As per your complaint a sore on the inner cheek can probably a canker sore and biting of cheek during sleep or there can be a habit of teeth grinding or bruise or teeth clenching. In case if she is continuously opening and closing her mouth and stretching her lip just now and is not a regular habit then it can be related to pain in mouth or any stress or anxiety related situation. For sore, you can apply numbing gel containing Lidocaine over it. Vitamin B complex should be given. Make her suck ice lollies and give her a soft diet. Hope this helps. Regards. 