pudding I am indeed a real life vet 
As long as he seems ok in himself, he's not passing blood, and is eating and, most importantly, drinking I wouldn't worry unduly. The 'don't panic limit' for a stomach upset in a healthy adult dog (so not a tiny puppy, elderly or with an existing health condition) is 24 hours as long as they are staying hydrated and seem perky.
There are two schools of thought with upset stomachs - starve or feed bland food little and often. I advise on a case by case basis, but with acute diarrhoea and vomiting in my own dogs I will usually starve for around 12 hours or so and then give small amounts of scrambled egg (no milk), or steamed white fish or chicken and a tablespoon of organic plain natural bio yoghurt to help the gut settle. Feed very small amounts of the above 4 or 5 times a day for a couple of days until they're back to normal. If you can get it, canned pumpkin is great for upset stomachs, I usually mix a tablespoon with scrambled eggs or steamed white fish and the bio yoghurt. Make sure it's plain, not the sweetened pie filling type though.
Urgent symptoms which require immediate veterinary attention are: refusing to drink and becoming dehydrated, becoming extremely lethargic and unresponsive, passing or vomiting blood, repeated but unproductive retching or straining (so trying to vomit or poo but not producing anything), sitting or standing in a hunched up position with the head down, called the 'prayer position', a tight, swollen. hard and painful abdomen - the latter three can indicate a blockage which is an absolute emergency.
Barring any of the above symptoms, if it persists for more than 24-36 hours then I would call the vet. You can buy probiotic paste online which is useful to have in the house just in case, especially if your dog is a gutbucket - Pro Kolin is a good one and it's cheaper online.
www.animeddirect.co.uk/protexin-pro-kolin-paste-syringe-60ml.html?gclid=CjwKCAiA8vPUBRAyEiwA8F1oDBUUrin3FVahJGOII10oXMDmsL0GHjHxOb4kjq6YWZW27uXG4J_6IhoCAVUQAvD_BwE