My son just turned a year and has 6 teeth. I noticed this morning that he has a back tooth that came in that is paper thin and had a bit of blood on it. I have searched on the interenet and can't find anything out. Can anyone help?

If the tooth has just come in it will just be the biting edge of the tooth you see. Give it some time to erupt some more. It's probably nothing to be concerned with. He'll have 3 more of the same coming in sometime soon. Wait and see, unless it is bothering him then have your dentist take a peek.