My Shi tzu was at groomers today. glands drained, short haircut, jumpy, whining often seems traumatized?

My dog is usually very happy gets along well with people and other dogs, he seems so wincing every two minutes a short little cry whine,,,,,,,,,,,, Jerky movements like something is hurting maybe on his bottom side I wonder if the groomer may have been rough or something when the glands were drained. A very short shaved cut maybe it is kind of poking them or jabbing his skin in places? I feel terrible he seems really affected after this can anyone relate to this? Wow