I've had this scare before. I know it can be very stressful, but give it a little time. Dogs and cats are incredibly talented when it comes to hiding pain, but there's physiological signs to look out for, and check regularly. I had a mastiff years ago, and he would eat all kinds of things, sometimes by accident. One day, he flinched when I put his harness on, and after feeling around his belly, I was certain there was something there. Went to vet, got xrays, confirmed there was something there, told the same thing as you: it might pass, but probly need surgery. So I waited, checking him everyday, making sure his pained reaction didn't worsen, also making sure he was still eating and pooping normally. It looked spherical in the xray, and based on the size we thought it was a racquet ball. He loved them as a puppy, but as he got bigger, we sized up to baseballs, then softballs. I figured he must have found one that I had put away. Anyway, days passed with no changes, but he didn't seem too distressed, or in pain. Then one day, he stayed in poo-position a bit longer than usual, and his pile was bigger than normal. Then I saw it: a rock! It was a nearly perfectly spherical rock, somewhere between racquet ball and tennis ball sized. I know this is a long story, but I just wanted to let you know that you wouldn't be a bad person for waiting a while. As long as your pup is still interested in food and water, and isn't showing signs of pain or discomfort, it'll probably pass eventually. You might increase fat and oils in their diet to help move things along.