Help please!! My dog ate chocolate?

My 2 year old Cairn Terrier ate a little bit of a kit kat then she started chewing on the wrapper which i think ha chocolate smudges on it! Its been a few hoirs and she is drinking a lot of water and panting she wants me to play fetch witj jer and leeps bringing her toy to me but what does the panting mrean? Should i take her to the vet?