Argh! Prickly Heat or Scarlet Fever?

OMG my baby boy has developed a rash all over his body and face. At first we thought it was just Prickly Heat so I stripped him off, gave him a cool bath, put some emollient cream all over him and just put him to bed in a nappy as the nights are so humid. Then I find out that another child at the childminders has had the same thing! Apparently his mother took him to the doctors and they just said he's fine and it's not contagious! Well guess what doc it bloody well is! My bb isn't ill at all with it it's simply just a rash. It can't be Scarlet Fever because they get a sore throat with that and feel ill so I'm fairly confident it's not that. I do just think it's a heat rash because apparently that is common in little ones as their glands haven't developed properly. I tell you what though the doc will be getting a visit tomorrow if it hasn't gone, but will that be a waste of time?