How long was the juice out before she licked it? Did it have time to go bad?
How is she acting?
How often is she vomiting?
Is she still eating?
What else did she get at the picnic?
Anyone offer her some snacks? Hotdogs? Fried chicken? Hamburger?
Okay, just making sure.
Yes, you can give her some pepcid. I would give her one tablet now and then tomorrow only give her a half tablet. Pull all food and only offer her ice chips for the rest of the day. Tomorrow I would start feeding her a small amount of boiled chicken and white rice. If she isn't better by tomorrow I would take her into the vet to be sure that the chicken juice wasn't contaminated by that time with bacteria that could have made her ill.