I have had tic syndrome on and off. My last bout with it was a few years ago after a strep infection. I have tics normally too but not to that extent. I had a large bout of tics from age 13-14. Then my face felt weird and I needed to tic quite often and also I squirmed because I never felt I sat right. My adult tics are more tensing like stretching my fingers and similar. Or stretching my shoulders. If I'm not allowed to tic it just builds up. For me I don't tic more from stress BUT that is a very common thing. It was once called nervous tic because people tic more while stressed. The thing is all people don't, only people with tics tic more under stress. So it's not brought on by stress just worsened by it.

The nature of a tic is that compared to other muscle jerks it is a voluntary movement. You know you are doing it. You know you will do it. The urge might just come over you but it is actually you who carry out the tic, while other muscle jerks might surprise you because they are completely involuntary. When I say voluntary I don't mean you are able to suppress them (some people can delay them), because it is in the nature of tic disorder that the urge is too strong not to obey.

Hope I'm making sense here.