All I can think is to keep him hydrated. Gently lift the skin on the back of his neck and let go. If it settles into place, he is ok for hydration. If it stays in position, or resettles slowly, get water into him, even if it takes a syringe or turkey baster to do it.

He MAY have swallowed a piece of string or even human hair that caused the soft stool.

You'd have to call around. Do you have a regular vet? They should have an answering service or an emergency # to call. Please try that.