Infected chicken pox?

[FagAshLil]

My 3 yr old has the pox, she's ok with but pretty covered.
She has 1 spot (the first) right on her knicker line thats looking a bit dodgy. It look almost black, quite large and has a red rim. It's also painful.
Does it sound infected?
I phoned docs first thing and have to phone back at 12 to speak to a doctor but thought i'd get an opinion here while waiting.
TIA

I'd get it checked. I don't think it should be black in colour. It does sound infected. My DD (4) has pox too, she's covered, with 1 big spot on her knicker line but it's not black. I've just put a pair of cropped trousers on her without knickers so there's no elastic irritating the spot. Hope she's ok.

Thank you. Saw doc this afternoon, is def infected so shes on antibiotics for a week.
We're really lucky with the weather, I'm putting her in just a dress and no knickers!