What town, state do you live in? Is there a community college nearby? How about churches? How old is your son? How about high schools - sometimes they give classes (not for credit, and sometimes in the summer)?
Look up something like "child actors" (your town, state) on the internet. I know in Austin, Texas there are a lot of acting classes.
But don't give up! Your son likes/loves acting - maybe he could put on a play for you and the family, extended family. There are plays at the library, even 1 person plays - like "Mark Twain Tonight," acted by one person (Hal Holbrook).
I'm pulling for you and your son

Kate