No worries there,
Now just like people, dogs can have diarrhea like this it can be caused by a range of reasons. With the waxing and waning signs and relapse you have described, I have to say that I'd be less concerned about diet itself (especially if he was fine before as well as he now goes a few days before relapse) and more concerned that this wee lad has an underlying GI agent triggering that loose stool. The reason it may appear to settle on the lighter diet options will be because they are easier to digest even if the gut is compromised. But once the original diet is weaned back, we start to see the compromised gut struggle again.
Now in regards ***** ***** agents, we can see diarrhea with bacterial, viral, parasitic (worms but also protozoa like Giardia, Coccidia, Cryptosporidia, etc), toxins (if he is nibbling something other then grass), nutritional, and general dietary indiscretions type causes ( the last 3 sounding less likely here). Even if he is kept on the lead, while he may not be a foreign body ingestion case, he will still be at risk of exposure to infectious agents if he can even stick his nose into any places another dog may have been (ie grass, plants, etc).
With all this in mind, we can start to narrow the cause of his signs. I am glad to see you have wormed him, since this will rule out some of our potential culprits. As well, if the vet did put him on a broad spectrum antibiotic, this does rule some common bacterial agents out but would still leave a number to consider. Now in regards ***** ***** at this stage, the best next step would be to consider submitting a fecal sample for analysis. This can be submitted directly to your vet before having any revisits and tested for common parasites, protozoa, viruses, and bacteria. This will allow you to pinpoint what is present in the GI and thus be able to target treatment effectively. Depending on the test findings, your vet and yourself could determine if an alternative antibiotic is necessary or if he needs to be treated with anti-protozoal medication to settle this. So, this would be a good option to shed some light on what may be triggering these loose stools (before panicking over dietary allergy issues at his age).
Further to this, I do just want to note that abnormal stools can sometimes linger when a previous infection (that perhaps was addressed by the antibiotics or worming) has disturbed the natural good bacteria population of the gut. Therefore, since he has had some treatments and his signs suggest mild GI digestive compromise, you could consider a probiotic support at this stage. Examples that would be worth using with your lad would be GI microflora supports like Fortiflora (More Info) or Pro-Kolin Enterogenic (More Info). As well, when we have loose stools of this nature, we wouldn't want to necessarily use a traditional anti-diarrheal but could benefit from treatment with a support like Protexin Pro-Fiber (which is available OTC at vet practices; example). This treatment is a probiotic support for the gut bacteria but also has a small dose of Kaolin which can help slow fecal transit and encourage normal stool formation. So, this would be a good option here.
Overall, there can be many triggers for diarrhea of this nature. Since he is young (and doesn't have the reserves of an adult) we do need to be proactive in trying to settle this for him. Therefore, since you have started ruling out common causes for this and seen no resolution, it'd be ideal to consider submitting a fresh fecal sample to the lab to be checked for common parasitic, protozoal and bacterial causes at this stage. Depending on the results, you will be able to treat effectively +/- the above supportive care to settle this for him.
I hope this information is helpful.
If you need any additional information, do not hesitate to ask!
All the best,
If you have any other questions, please ask me – I’ll be happy to respond. Please remember to rate my service once you have all the information you need. Thank you : )