Hello & welcome, I am Dr. B, a licensed veterinarian and I would like to help you with your wee one today.
Now we can see upper and lower GI upset of this nature caused by a range of agents. Common ones at Max's age would be bacterial or viral gastroenteritis, parasites, protozoa, dietary indiscretions, inflammatory GI issues (ie IBD), and while hopefully less likely, toxic or foreign body ingestion.
With all this in mind, if he is bright and bouncy, then we can try some supportive care first to see if this is just a bit of benign upset or related to a dietary indiscretion. First, your bland diet options are spot on. Of course, you do want to make sure to stop the treats (including the dental stick and chewie) and offer these bland meals as a few small ones over the course of the day. This will make the gut's work easier, facilitate nutritional uptake, reduce vomiting post-meals, and reduce diarrhoea volumes.
Further to this, you can consider trying him today on a GI soothing anti-diarrhoeal treatment. As I am sure you appreciate, these would not be a cure if his diarrhoea is being caused by an infectious agent (ie bacteria will require antibiotics, parasites or protozoa will require anti-parasitic treatment, etc). Still it can slow the diarrhoea to aid the body to absorb more water/nutrients. Furthermore, these treatments will coat the GI and could just settle the GI upset and reduce nausea too. In regards ***** ***** options for your wee one, the ones we most commonly use in dogs is Kaolin/Kaopectate (More Info/Dose ) or PeptoBismol (More Info/Dose ) available from your local pharmacy. Furthermore, Protexin Pro-Fiber (which is available OTC at vet practices) would be another option. All will soothe his stomach and slow diarrhoea and the Pro-Fiber has the bonus of providing support to the delicate good bacteria of the GI. So, you can consider trying these as a short term means of trying to soothe his upset GI.
Overall, we do have a few concerns when we see GI upset of this nature. Still, if Max is bright, keeping hydrated, and his signs are mild; then we can use the light diet combined with one of the above treatments to see if we can soothe his gut and halt his signs. Of course, if you find he doesn't settle by Monday or starts to feel poorly, then we'd want to consider a check with his vet at that stage. If possible, you can take a fecal sample in for them to see what he is passing. Depending on their exam and fecal findings, they will be able to advise you if he has picked up something infectious and dispense appropriate treatment (ie antibiotics, anti-protozoal medication, anti-nausea medication, etc) to clear this for him.
I hope this information is helpful.
If you need any additional information, do not hesitate to ask!
All the best,