Dog not settled after anaesthetic...help !?

My dog had an anaesthetic this morning as he needed an x ray, and since he came home he has been crying, howling, restless, and will not settle. He has now been sick. He is constantly by the door wanting to go out but when i take him out he can`t `go` although he is trying to. Has anyone got any ideas what could be going on please before i ring the emergency vet out ?