how do I know if my 10 month old has the measles?

He had a brownish rash on top lip last week then got a fever of 102-103 for a couples days with a phlegmy cough but no runny nose. Still has cough but no fever. But now has a redish rash all over his body

Measles typically begins with a mild to moderate fever, often accompanied by a persistent cough, runny nose, and inflamed eyes. The rash consists of small red spots, some of which are slightly raised which gives the skin a splotchy red appearance.
See doctor if you think your child may have been exposed to measles or if your child has a rash resembling measles.