Hi Katy,
Welcome to the NeuroTalk Support Groups. Here is some info. that may be helpful to you. It is actually not uncommon for children who have comorbid conditions as well as their tics to have problems with meltdowns. Look for particular triggers, e.g. is he more prone to having these meltdowns when he gets home from school.

Rage Attacks or Storms - Leslie Packer TS "Plus"

Overview of "Rage Attacks" - Leslie Packer TS "Plus"

Let us know more and perhaps we can make some suggestions. My son had this problem when he was young (adult now) but he is also on autism spectrum and in retrospect I see how that was a huge impact. His days in school were pretty darn stressful for some years there when he was young. He spent a lot of his time and energy trying to suppress his tics. He did a lot better when certain modifications were put in place to make his days less stressful. Long story.

Let us know more.