URGENT: FROTHING MOUTH AND SEIZURE IN MY DOG

My dog quickly started having/experiencing a severe seizure. He's having froth coming from his mouth and can't stay still. I don't know what to do next. Please help! Is this a sign of something really bad? I'm so scared, he's my best friend. My Dog Is Having a Seizure, Foaming at the Mouth It's incredibly frightening to witness your dog/your pe