When ever my dd gets angry or upset she will either bite or slap herself pretty hard. She's not broken the skin when biting yet but she leaves a fairly clear impression. I feel like I've tried every tactic; ignoring her, restraining her, cuddling her (I may get bitten if I'm close enough). It happened in Tesco's the other day and I got some very strange looks as my dd began to hit herself round the head!
When it's all over she'll sometimes say, "I really hurt myself but I didn't mean to". Help!