Is your dog up to date with worming/flea treatments Broomsticks, and is the dog a rescue or a pup? Rescues and puppies often have upset stomachs as they settle into a new environment. Stay with rice or pasta, and skin/fat free plain boiled chicken or white fish for about a week. Feed small meals frequently. Aim to gradually increase amounts, decrease frequency till you are feeding twice a day for adult dogs, 3 or 4 times a day for youngsters. Then, start to introduce the diet you plan to feed.
Have you tried more than one dried food? There is an excellent website called dogfoodanalysis.co.uk which will tell you which of the many varieties of kibble are good quality.
Dogs on decent quality food do smaller, less smelly poohs.
Eating pooh is another familiar behaviour in some rescue dogs. Always pick up immediately so the dog doesn't get into the habit. Some people put a bit of pineapple into the dogs feed, as dogs with a pooh eating habit evidently don't eat it if there is pineapple in it (why do they eat it in their food then I wonder) The other thing some folks recommend is to leave the pooh in place, put a bit of chilli on it, and let the dog discover how unpleasant that is with the aim of putting them off the habit. I've not tried either of those things, but with rescue or foster dogs with a pooh eating habit, I've just made sure they never get the opportunity to do it. Give them lots of other things to think about - good luck