CRITICAL: FROTHING MOUTH AND SEIZURE IN MY DOG

My dog suddenly started showing signs of a terrible seizure. He's having froth coming from his mouth and can't stay still. I don't know what to try. Please help! Is this something I should call a vet about immediately? 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 you