It's ridiculous that your doctor's not available. If he doesn't even have a service to cover him I would consider that a very black mark against him. And it's especially bad after he has just recently prescribed you a scheduled and possibly addictive drug. I personally would be looking for a different psychiatrist. If you end up in the hospital as a result of his neglect then I would consider him liable.

In the meantime I agree with the posters that a hospital ER visit is a thought, though it's unlikely they would give you an emergency dose of that particular drug. Also why not drive to his office as Misssy2 suggests?