IMMEDIATE: FROTHING MOUTH AND SEIZURE IN MY DOG

My dog abruptly started having/experiencing a terrible seizure. He's having froth coming from his mouth and can't stay still. I don't know what to do. Please help! Is this an emergency? I'm so scared, he's my best friend. My Canine Companion is Experiencing a Convulsions, Frothing at the Mouth It's incredibly frightening to witness your dog/you