hmmm mine reverse sneeze alot after vomitting but it does not last this long - make sure he checks cpli and tli for pancreas with blood work to make sure vomitting was not from pancreatitis. Also make sure he checks heart real well. Was it a honking sound? that is collapsed trachea -- go to you tube and type in reverse sneeze and type in collapsed trachea and see which it was. Hopefully it is just back up from vomitting but the shaking part scares me - was it like a seizure type shaking or scared shaking? So sorry you are going through this
