I had this with Flicka way back, used the pro-biotic but the thing which really cured her was Hills Prescription diet "Gastrointestinal Biome", I bought a small bag and it was excellent. I have a bag by me 'just in case'.
Just a thought, and it may well be completely unhelpful, but do you have bird feeders in your garden? I ask because Joy had very similar problems as a puppy, and like Stanley, didn't seem at all unwell. Testing by the vet showed that she had Campylobactor (unsure of spelling!) caused most likely by eating the food that had spilled off the bird table. Once this had been treated and the position of the bird feeders was changed we had no further problems. I hope Stanley's better soon.xxx
Some dogs are allergic to chicken. I put Flicka on Millies Wolfeart, but first of all I gave her the Biome food to sort her tummy.
Homer was sensitive to chicken. So why I think I should change.
What a little darling x
it would always take 4 days to start to improve, he was completely fine otherwise! Just really bad poos! I did pre probiotics and pumpkin flakes in his food daily to help as best I could
The tippy toe stretch to look out the window 