IMMEDIATE: FROTHING MOUTH AND SEIZURE IN MY DOG

My dog suddenly started going through a terrible seizure. He's having froth coming from his mouth and can't move. I don't know what to do next. Please help! Is this something I should call a vet about immediately? I'm so scared, he's my best friend. My Canine Companion is Experiencing a Convulsions, Frothing at the Mouth It's incredibly frighte