What is it?

[Emmabatz]

My son who's 6 months old woke up with this mark around his thigh. It's not raised or hot, and disappears when you press it. It fades during the day but by the morning it's really red again. I showed my mum who's had 5 kids, and she hasn't got a clue. When it first appeared I thought maybe he slept awkward in his growbag and caused a blood blister, but it's comeback and it's exactly the same and he's in a bigger growbag. Any ideas?

Is his whole leg red?

I can only see the mark on one of the photos.

On another photo it almost looks as though his entire leg is red from mid-thigh downwards. It almost appears like sunburn (not saying it is!).

To be honest, with a baby I'd always err towards getting checked out with an unusual symptom that can't be easily explained