Help - rash on 2 year old

[annobal]

DS2 has come out with a raised rash on his face today - started at lunchtime and has gotten worse throughout the day. Should I be worried? Advice please...

has he eaten anything unusual? could be an allergic reaction

Is the rash anywhere else? Limbs, Body?

Does the rash blanche?

Other than the rash is he feeling well?

Are they little blisters?

Has he had a cold, cough, runny nose?

My Ds's both had a rash 2 weeks ago on their bodies, face etc. I was really worried but it turned out to be viral and nothing else at all.