Weird rash on dd

[Forgetfulmog]

Hi

Dd is 5 months old and has this weird rash on her left knee. It's about an inch below her left knee cap & comes round in an arc so that it looks a bit like an inverted c. First noticed it a couple of nights ago, but I've just changed her & it looks slightly worse (darker) - it might just be the light though as I use a dim light for night changing. It's not raised, doesn't appear to be itchy or bothering her. Colour is a sort of faded dark pink.

Any ideas???

Thanks!

Is she otherwise well?

Sorry should have said. Yes she's fine - alert & happy & feeding fine (ebf).

Actually looking at it in daylight, it's not a rash at all - more a mark. Very weird

Where abouts are you? Is there any chance at all that she may have had a tick bite? For example, do you live somewhere where there are ticks/have dogs/etc.

I don't think so, we don't have dogs nor do our families & we live in a city. It's just strange - I looked at it again when I was changing her just now & you can now barely see it. Ill have to check again tonight. I'm wondering if its maybe some kind of strange skin pigmentation that is more obvious in artificial light. She's my first born so do get rather obsessed when I notice anything unusual about her!