First, I am glad to hear those more serious signs are all normal. That said, I am quite concerned to hear that he has eaten acorns. This is because these can certainly cause GI upset with belly cramps, diarrhea, vomiting, weakness, and lethargy. As well, they are the perfect size for causing blockages. So, we need to tread with care if there i any chance he has had these. Of course, we also have to be wary of that being a red herring as these signs could also be seen with gut infections, pancreatitis, parasites/protozoa infections, and general dietary indiscretions,
With this all in mind, if you think he ate quite a few acorns, we'd want him seen now to rule out toxicity and/or blockage. Otherwise, we can at least try to to settle his nausea and try to get him eating. To start, if he hasn’t just vomited (since otherwise we’d need to rest the stomach for a few hours first), you can consider treating with an OTC pet safe antacid [ie Pepcid (More Info/Dose @http://www.petplace.com/article/drug-library/library/over-the-counter/famotidine-pepcid), Zantac (More Info/Dose @ http://www.petplace.com/article/drug-library/library/over-the-counter/ranitidine-hcl-zantac),etc]. Whichever you choose, we’d give this 20 minutes before offering food to allow absorption. Of course, do double check with your vet if he has a known health issues or is on any medications you haven't mentioned. Also if you give this and he cannot keep it down due to nausea that is usually a red flag that we need to bypass his mouth with injectable anti-vomiting medication from his vet.
Once he is more settled, you can plan to try small meals of a light/easily digestible diet. Examples you can use are cooked white rice with boiled chicken, boiled white fish, or scrambled eggs, or meat baby food (garlic/onion free only). Or if he refuses to eat but we have settled the vomiting, you can potentially syringe feed watered down puppy food to get some nutrition and fluids into him.
Since dehydration is a risk here, we need to keep an eye on his hydration. To check this and make sure dehydration isn’t an issue, there are a few parameters you can test. Further to checking for gum moisture, you will want to make sure his eyes are not looking sunken and that he doesn’t have a "skin tent" when you lift the skin. To see how to check these, you can find a good video HERE (http://www.ehow.com/video_12232503_dog-dehydrated.html). If you do see any of these signs already, then that would be our cue to have him seen before this becomes an additional issue (especially since its often dehydration that makes them feel unwell).
Overall, a wide range of agents could trigger the signs we are seeing but acorns are a real worry here. Therefore, we’d want to start supportive care to try to settle his stomach. Though if he cannot keep that or water down, appears dehydrated already, or doesn’t respond to the above within 12-24 hours (since he is older); then we'd want to get his vet involved. They can assess his hydration, rule out fever, ensure nothing in his stomach that shouldn't be, or any sinister viruses present. Depending on their findings, his vet can treat with injectable anti-vomiting medication, fluids, +/- antibiotics to settle his stomach and get him back feeling like himself.
Please take care,
If you have any other questions, please ask me – I’ll be happy to respond. **Afterwards, I would be grateful if you would rate my service by clicking on the "Rate my Expert' button at the top of the page as this is the only way I am credited for helping you. Thank you for your feedback!: )