IMMEDIATE: FROTHING MOUTH AND SEIZURE IN MY DOG

My dog suddenly started having/experiencing a serious seizure. He's having froth coming from his mouth and can't move. I don't know what to try. Please help! Is this a sign of something really bad? I'm so scared, he's my best friend. I Think My Pet is Having Seizures, Excessive Drool It's incredibly frightening to witness your dog/your pet/my f