'Dirty' patch on DD's face

[Rugbymumof2]

Yesterday I saw what I thought was a dirty patch on DD's (9yrs) face just above the corner of her mouth in line with the nose.
She used a wipe but it wasn't dirt and didn't come off, to feel the skin is smooth and like that of the skin around it but is it noticeably darker and seems to have appeared suddenly.
Any ideas, it doesn't feel like something to rush off to the GP about, would the pharmacist be worth trying?

She's not just started to play a brass instrument?

It's fairly common to develop a bruise there when they first play. Dh (and several others I know) have memories of mum trying to wash the bruise off.

She does play an instrument but has done for about a year now.
It could be a bruise, will see if it goes over the next few days.

If she's trying a different technique or playing for longer then it can bruise too.