Dog has been absolutely freaking out?

My dog was just neutered 3 days ago (he is a 5 month old German Shepard Dog). Yesterday and today he has had absolutely psychotic episodes in our house. He will start to look around and then bolt around the living room in circles urinating and defecating all over the floor. When I try to get near him to calm him down he air snaps at me and screams these absolutely blood curdling screams. The only way I can get him to calm down is to put him in his crate, but tonight he freaked out in there as well. The vet prescribed Tramadol for the pain, and we are wondering if this has anything to do with it. We are very scared for our dog as this is absolutely frightening behavior.