Is my dog poisoned or something worse... ?

My dog has acted very nervous and just doesn't seem like herself. She's been drooling and foaming at the mouth and vomiting almost all day. Since I brought her in she's vomited about 5 times. She drank some water and ate a dog treat though. She's been staggering a little bit and shaking, and it looks like she's breathing harder. I'm taking her to the Vet very soon. What could be wrong with her? Poisoned? This morning she seemed perfectly fine, hyper and normal like she usually is, help?