Shingles is the chicken pox virus re-activating in you. You are therefore contagious and can pass on the virus. Your DS may be incubating it. He may be OK, he may not - you'll find out in a couple of weeks' time. The longer the virus has been incubating, the more contageous the infected person: most people catch it from a person who gets the spots 1-2 days after contact.

I say give playgroup a miss until 3 weeks after your shingles has ended, to be safe. Or hold a pox party at your house. Up to you.