Did my dog swallow a pill!?!?

My dad is elderly, and drops a lot of pills. We pick up any we can find, and my dog knows already what not to eat. Recently, my 12 year-old chihuahua has been vomiting and shaking. her mouth sometimes shakes, like shes struggling to close it, and has been eating gass to help her vomit. For undisclosed reasons I cant take her to the vet. How can i help her at home? I'm still unsure if she swallowed a pill!