Worried son had measles

You don't say how long ago this happened, or if you are living in unvaccinated community or otherwise suspect exposure. Chances are very small that your baby had measles, which are exceedingly rare in most places, that's why the current outbreaks are in the news. At 6 months, you would have known if he was exposed at daycare or in the family, or if there was an outbreak in your community.

It's much more likely it was another rash like roseola or Fifth's disease. (There are several more possibilities, but these look most like measles. My daughter, an RN, was worried when her son was about the same age, and went to the pediatrician despite my assurance it was Fifth's, which the doctor confirmed.

In the unlikely event your son did have measles, chances of developing SSPE also are VERY small - estimates range from 1 per million to 1 per 5000. As your son grows up, there are many other things more likely to cause injury than this.

Please don't spend his precious childhood worrying about remote dangers, but instead spend your time enjoying these years and watching him develop into a unique person.