Schnauzer

My 6 year old gets tics on and off, right now it's a blinking tic. They do seem to coincide with begining of Spring and Fall. He had been 6 months without any, and he's a picky eater so his diet doesn't vary so it can't be the food. His sitter mentioned this morning that she thinks it coincides with growth spurts. Has any noticed this in their children? He does have a genetic predisposition for TS, my brother has it.