Kat’s simple tip for figuring out the severity of a bloody mouth injury:
My mother in-law was over the other day and when we discovered my 14-month-old inexplicably had blood in his mouth (and no idea what caused it or where he was hurt). She told me to go get a white washcloth and wet it with cold water. Then she folded it in half and let him bite down on it. The telltale spot on the cloth showed that he had bit into his upper gums with his sharp lower teeth, not a major injury. I’m not sure if every little one will bite down on a cold wet washcloth, but mine sure will. I will be using this one a lot until he reaches the age where the sight of blood scares him. Then I will switch over to the hack you published once about using a dark colored washcloth to hide the blood!
You can get cheap, white cotton washcloths by the bundle at the big box bed-and-bath stores. I bought a ten-pack a couple of years ago, and they come in handy for everything (like the cloth diapers did when my kids were little).
Related: Cold washcloth helps teething