DS 18 months woke up shortly after going to sleep with blood on his sheets. Its pink rather than red so its diluted with saliva, and I can see a cut in his mouth. My best guess is he's chewed his cheek through teething maybe? He seems ok in himself, a bit grumpy today and was happy as larry after I got him up and but the tv on so I could get a look in his mouth. Is this normal?