Good, I am glad to hear you aren't seeing coffee ground like vomit (which is the appearance digested blood tends to take and is something to keep a close eye out for with this situation) and that she is otherwise herself.
Now if Lucy ate sand, we need to tread with care. This is because sand can cause a few problems for our dogs. First, if they eat quite a bit we can see blockages in the intestines. Otherwise and more often, we can see severe GI upset +/- gut damage due to the abrasive nature of the sand on the delicate gut mucosa.
With this all in mind and since she is only showing mild signs, we can try some home supportive care First, to counter her nausea and as long if she hasn’t just vomited (since otherwise we’d need to rest her stomach for a few hours first), then you can consider treating her with an antacid. Common pet safe OTC ones we can use include 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), or Tagamet (More Info/Dose Here @ http://www.petplace.com/article/drug-library/library/over-the-counter/cimetidine-hcl-tagamet)
Whichever you choose, we’d give this 20 minutes before offering food to allow absorption. Of course, do check with her vet before use if she has any known health issues or is on any medications you didn’t mention. As well, if you try this and find her nausea too severe to keep it down, then that is usually a red flag that we need her vet to bypass her mouth with injectable anti-vomiting medication.
Afterwards, we’d want to start her on a light/easily digestible diet. Examples you can use are cooked white rice with boiled chicken, boiled white fish, cottage cheese, scrambled eggs, or meat baby food (as long as its garlic/onion free). Whichever you offer you can add some fiber (ie canned pumpkin) to try to coat the sand and push it through. As well, we can even start adding OTC cat hairball treatment into her food as this is a mild GI lubricant that can help the sand slip through.
Of course, while we encourage it all to pass, we need to keep a close eye on her. Warning signs of trouble would be include paling of the gums, belly pain, black stools or blood/brown vomit, anorexia,or restlessness. Any of those signs and we’d want Lucy checked urgently by her vet +/- an xray taken for us to assess if the sand is causing harm.
Overall, these are situations where we do need to be careful with our dogs. Its good that Lucy's signs are mild and she isn't sore from the sand she ingested. Therefore, at this stage, we can try the above to soothe her stomach and help this all pass. Of course, if her signs linger, she cannot keep the above down, or develops any of those warning signs; then we'd want to have her seen urgently by her vet to be checked and so that they can start gastroprotectants and symptomatic care (ie injectable anti-nausea medication, antibiotics, etc) to settle this for her.
Please take care,