Black blister

[chocolatecakemakesmefat]

This was nappy rash on 3.8 year old and has now turned black this is infected isn't it?
(Before I get moaned at I've already phoned NHS and they will phone back within 3 hours)

Pic of said blister

Looks very sore, and yes does look infected.
What did NHS say?

NHS said to give him calpol and take him to doc if still bad this morning , it has actually burst through the night it's rank so going to keep it clean and hope that's the end of it

Hope it is ok now!