What should i do when my dog has seasures?

He is a german shepherd about one and a half years old, he had afew seasures about 6 months ago so we took him to the vet and they gave him a prescription for barber tall or sumthin and we give that o him 2x a day and he has not had a sesure in awile except he had two today, one at about 6 pm and one at 12am we are taking him to the vet tomorrow... but if he has another what should I do...? Try to hold him and keep him from moving and kicking? Or jus let him be until its over? I've been patting his stomach and back when he had one... any answers will help thanks