5 month old - rash all over back

[naturopath]

Hi - my 5 month old ds just came up in a rash all over his back and some of his front this afternoon / evening. Seems otherwise ok I think.. does seem to be itchy though, as was v restless this afternoon and itching his head in his sleep.. any ideas as to what this could be? Do we need to see a dr?
thanks!

What's the rash like? Is it white wheals surrounded by red (hives), is it tiny red spots - what?

have you done the glass test?

tiny red spots.
Oh gosh, I didn't even think it would be anything dangerous until I just posted this..
He didn't seem at all ill when I put him to bed.
haven't done the glass test.

has he been poorly recently? it could be just a viral rash

no, he's been fine..

I feel a bit silly for asking now, as after suddenly googling the type of rash it is.. I think that it might be heat rash. We were at friends today for lunch and stayed the whole afternoon - they had their heating on really high, and he had a couple of naps in his snowsuit (as I took him outside for walks and then didn't take the snowsuit off, although I did take off blanket and unzipped the snowsuit to keep him as cool as pos without waking him).

He did actually recently have a fever, and on about the 4th day of fever came out in a rash all over his body (I think it was roseola). That was a couple of weeks ago, and the rash looked different to this one (that one was like mottled skin all over whereas this is tiny raised spots).

thanks - I feel reassured now.

oh yes that's probably what it is
don't feel silly though, better to ask/google and be reassured than to leave it and worry or have it turn out to be somethijng nasty