My ten year old has a tic--well, probably a couple. A few years ago he started quietly clearing his throat while reading or watching tv. He doesn't do that much anymore, but he has been nodding his head since...hmmm, about last August. He tends to do it while he's watching tv or reading, or being read to. The head nodding tic came on very suddenly, which made me nervous. I took him to the doctor that week, who gave him an exam that came back normal, and sent him for blood work that also came back normal. I scheduled an appt for him at UNM dept of pediatric neurology as soon as I could, but it was months later. By then he was still doing it, but I wasn't as worried.
The doctor there was amazing. She couldn't have been less concerned.

She gave us some tools to help in case he ever was bullied about it, some handouts and links to websites. She said tics in kids are common, they sometimes go away, and sometimes don't, but even if they don't, you can still do anything you want with your life and gave my son an example of a surgeon she worked with who had it--it didn't impede his ability to operate at all. She said she absolutely did not need to see him again.
I have noticed a possible tic in my younger son at all, but am trying to be more relaxed about it. They really are common.
Some people say tics can be a result of a magnesium deficiency. You could try epsom salt baths or a supplement like Natural Calm (watch out--too much can result in loose stools). You can try to figure out the trigger...for some kids it's anxiety, others it can be allergies (happens mostly in the spring, for example). If you can work on lessening the trigger, the tics might slow down a bit, too.
Hang in there. They really are super common.