First, I have to note that the swelling you have described doesn't fit with her other signs. Therefore, if you can post a photo (using the paperclip icon over your text box or posting it anywhere else and then pasting the link here for me) that would be grand.
That aside, if she cannot even keep water down, then we need to tread with care. Especially as my concern with Daisy is that while we can see GI upset with ingestions of this nature, her signs do also raise suspicions of pancreatitis. This is a condition we often see when sensitive dogs indulge in fatty/rich people foods. And it can cause intense nausea that often requires injectable anti-vomiting treatment to halt before we can even consider oral treatments.
Now if you think she can keep a wee bit down, then we can try an oral supportive care measure at home. Unless she has diarrhea, we'd not use the Pepto Bismol. Instead, it would be better to use an antacid. There are a number of antacids that are available over the counter and pet friendly. I would advise only treating with one, but the two I tend to use are: Pepcid (More Info/Dose @ http://www.petplace.com/article/drug-library/library/over-the-counter/famotidine-pepcid) or Zantac (More Info/Dose @ http://www.petplace.com/article/drug-library/library/over-the-counter/ranitidine-hcl-zantac). These are usually given 20 minutes before offering food (to allow absorption) and of course you want to double check with your vet before use if your wee one has any pre-existing health issues or is on any medications you haven't mentioned.
If she can keep that down and settles, then you can try her with a light diet. Examples of an easily digestible diet include cooked white rice with boiled chicken, boiled white fish, scrambled egg, or meat baby food (as long as its free from garlic or onion powder). Ideally, we want to offer this as small frequent meals to keep the stomach settled. These will help with both GI upset and pancreatitis.
Overall, we do have a few concerns for Daisy's signs after eating this macaroni salad. And I would note that if she cannot even keep any water down, we'd need to be thinking about getting her local vet involved to bypass her mouth with injectable treatment. Otherwise, you can try the above antacids for her, but Pepto is not ideal. If you do use the above and she settles, then do put her on a light diet, monitor, and do post a photo of this odd swelling so I can check that for you.
Please take care,