I am sorry to hear about Ellie eating 2 ounces of milk chocolate M & M's.
There are several types of Lindt chocolate, so I am not sure how many ounces he ate.
An 8 pound pup would need to eat 1.2 ounces of pure milk chocolate to see symptoms of drooling, nausea, vomiting and diarrhea and almost 2.5 ounces of milk chocolate to see hyper-excitability and an elevated heart rate.
At higher amounts we can see muscle tremors and possible seizures.
The good news is that M & M's are not pure milk chocolate, and are candy coated, so although she ate 2 ounces of candy she did not eat 2 ounces of milk chocolate.
If it has already been 2 hours it is likely the chocolate is out of her stomach and it is probably too late to induce vomiting.
And you have already given her anti-nausea drugs.
At this point you may not be able change things much at home, all you can do is watch her for further symptoms now.
If it has been less than 2 hours you can try taking her to an emergency clinic to have them try to induce vomiting, but if she took a drug like Cerenia (maropitant) they may not be successful.
Since she has already had anti-nausea drugs, and she may not have eaten enough chocolate to cause her trouble, you can try a watch and see approach.
I would encourage you to get her to drink as much as possible and to get her out to urinate frequently. Chocolate toxins are metabolized out through the kidneys and can be reabsorbed from the bladder so we don't want them to sit in her bladder for long.
In most cases mild chocolate toxicity is out of their system in 24 to 48 hours. We generally begin to see symptoms, if they eat a toxic amount, within 4 to 6 hours.
It may help to with-hold food for the next 12 hours to stop intestinal spasms.
If she seems at all nauseous to try and settle her stomach you can give either:
1) Pepcid ac (famotidine) at ¼ of a 10mg tablet per 5 to 10 pounds of body weight every 12 hours
2) Prilosec (omeprazole) at ¼ of a 10mg tablet per 5 to 10 pounds of body weight every 24 hours
These are acid reducers and should help him feel less nauseous. They are quite safe and can be used for several days if needed.
Then after her 12 hour food fast to decrease the symptoms of stomach upset you can feed her a bland diet for the next couple of days. A homemade bland diet is a mix of 1/3 boiled minced white skinless chicken or lean boiled hamburger and 2/3 boiled white rice mixed with some low salt chicken broth to make it easy to lap up and swallow. Feed small meals frequently.
If you do notice a very rapid heart rate (more than 160 beats per minute in a small dog), repetitive tremors, or seizures then she should be seen by a veterinarian on an emergency basis for treatment. They can use injectable medications to control her heart rate and stop the seizures until the toxic levels fall. But with the amount she ate you may not see any symptoms or only mild stomach upset.
Best of luck with Ellie, let me know if you have any further questions.