Anyone know what this could be on DD's leg? (Pics)

[notaregularmom]

I first noticed this on her leg this morning, it goes around her whole leg and is really straight, my first thought was she must of drawn on herself but she's only 3 and couldn't draw that neatly, next thought was maybe she had put a hair band around her leg but just got her out the bath and it's still there I'm totally baffled as to what it can be and google isn't much help and I've asked her and she's doesn't seem to know either.

How weird. Sorry ,no help

Nothing in her bed I've checked it all, and she wears shorts pjs to bed

It's been on there for 2 days now and hasn't faded, if something was tight on there surely it would of faded a bit bulky now?

Is it a friction mark somehow, that wouldn't fade quickly?

That's so weird

Have you put her in the bath and see if it's dye that washes off
Failing that I'd pop to the pharmacy

@Somanysocks I was just wondering about a friction burn. OP - is the mark hot or itchy for her? Possibly put savlon or some antiseptic on it.