The following is from a kids health website:
Signs and Symptoms
While measles is probably best known for the full-body rash that it causes, the first symptoms of the infection are usually a hacking cough, runny nose, high fever, and watery red eyes. Another marker of measles are Koplik's spots, small red spots with blue-white centers that appear inside the mouth.
he measles rash typically has a red or reddish brown blotchy appearance, and first usually shows up on the forehead, then spreads downward over the face, neck, and body, then down to the feet.
Measles is highly contagious. When someone with measles sneezes or coughs, he or she can spread virus droplets through the air and infect others.
The most important thing you can do to protect kids from measles is to have them vaccinated according to the schedule prescribed by your doctor.
Treatment
The symptoms of measles usually lasts for about 2 weeks. It is highly contagious, and 90% of people who haven't been vaccinated for measles will get it if they live in the same household as an infected person.
A child who is diagnosed with measles should be closely monitor for fever and other symptoms to detect any complications. In some cases, measles can lead to other health problems, such as croup, and infections like bronchitis, bronchiolitis, pneumonia, conjunctivitis (pinkeye), myocarditis, and encephalitis. Measles also can make the body more susceptible to ear infections or other health problems caused by bacteria.
If fever is making your child more uncomfortable, you may want to give a non-aspirin fever medication such as acetaminophen. Remember, you should never give aspirin to a child who has a viral illness since the use of aspirin in such cases has been associated with the development of Reye syndrome.
As with any viral infection, encourage your child to drink clear fluids: water, fruit juice, tea, and lemonade. These will help replace bodily fluids your child loses in the heat and sweating of fever episodes.
Use a cool-mist vaporizer to relieve cough and to soothe breathing passages. Clean the vaporizer each day to prevent mold from growing. Avoid hot-water or steam vaporizers that can cause accidental burns and scalds in children.
Kids with measles should get extra rest to help them recover. It's usually safe for a child to return to school 7 to 10 days after the fever and rash go away. But to be sure, check with your child's doctor.
Keep track of your child's temperature. Let the doctor know if your child has an earache, since this may be a sign of an infection.
Remember that measles is very rare, and a child who is properly vaccinated is extremely unlikely to contract the disease.
--------------------------------------------------------------------------------------------------
He may have measles, or it may be chickenpox. Or he could just have a bug that has caused a rash. Best thing is to take him to the doctor. Hope he feels better soon.