Hello Maria, I emailed you privately as well. If you are taking him to Ringwood Vet, they have a great Rep. See if they have office hours on Sat. If not you can call Greenwood Lake Animal Hospital. They are in on Sat.
What did your breeder suggest you feed him? Have you changed his food since he came home? Maybe it's too rich for him. I have just learned recently (having a 9 and 10 yr old sons) that I need to re-baby proof the house. As Chaplin (our pup) got bigger he was stealing off the counters, and other naughty puppy stuff. It was my fault. It's been a long time since I had a puppy or a baby/toddler in my life. Chaplin never hurt himself, but could have since he needs supervision. Don't worry about the puppy classes. He's so young. Get him feeling better then worry about that later. Hope he feels better, Jennifer