Posting here for traffic in the hope of swift response to calm DD down.
She has a rather big lump on her gum, which hopefully you can see on the attached pic. It actually looks like 2 small lumps, with a dark centre? She said it doesn’t hurt, but is panicking like mad. I’ve sent her down to brush her teeth, and she’s promptly vomitted 
I’ve had a quick google and think maybe a gum abcess but I’m not too sure.