I had a scare with our puppy Conner (RIP) once ate a hershey bar. I was panicking until I looked it up on line and he would have to eat like 60 milk chocolate bars for it to be fatal. Baking/dark chocolate is a lot more dangerous. A lot of trainers use M&Ms. Personally, I avoid chocolate because it is a laxative. Crating is pretty harsh on a dog that has not grown up that way. I would suggest a room they can share with a nice window view and plenty of toys and comfy nap places.