My dog may have eaten chocolate...?

I came home and found hershey kisses wrappers on the floor, and I'm not sure if my dog ate them or my niece. It is about 15 hershey kisses, milk chocolate. I called the vet, and he has not shown the clic signs of poisoning, he has actually been very playful and acting normal. The problem is, for 2 days now, he has not pooped. He will squat like he wants to, but nothing will come out. He is a 20 pound labradoodle. I heard that feeding canned pumpkin, adding metamucil, and adding mineral oil are some remedies. Can someone tell me for sure what is a safe route to try and cure constipation at home? I will have to take him to the vet if it keeps up for another day.