He has the measles.
roseola―rose-rash
a contagious disease that causes eruptions on the skin, called German measles
I got a rash.
{ecxema} on the skin caused by perspiration
What about the rash?
The rash is, um, also incredibly contagious.
I got a rash.
pityriasis in which an itchy rash develops over the trunk and extremities