[Princes mom]

Ian vomitted night before last, but seemed to be fine afterwards. I gave him a little boiled chicken and rice with extra water the next day for all of his meals. He normally poops 2-3 times a day, but he hasn't done anything today. This morning for breakfast he had his kibble (Fromm Chicken/Veg) mixed with a teaspoon of pure canned pumpkin. This afternoon he had about a tablespoon of pure canned pumpkin for his snack. At 5p for dinner he had a little kibble with pumpkin. He has been walked three times today, and nothing!!!!! I noticed that he tries to eat grass every few steps, which I try to prevent him from doing.
This has never happened before for such a long period of time, and we are concerned. Usually the pumpkin works within a couple of hours, and leaves his poop nice and somewhat firm. He is not acting any differently, and is not acting as if he is in pain...he just won't poop.
My neighbor uses mineral oil for her yorkie, but I don't know about that. We'll be at the vet at 7a if nothing happens tonight.
Advice needed and appreciated...thanks!!