He most definitely needs to be checked out by your vet. It sounds to me like epileptic seizures, although there are other things that could cause this type of activity. Make an appointment for him ASAP.
Ghilly
Welcome...What your describing is too dangerous of a situation for us to guess at....Please, seek help from your Vet ASAP...Try to record/video one of these episodes so your Vet will be able to see it....If you have not already, you need to get your dog to his Vet...I wouldn't wait much longer.....Let us know what you find out....Karla