Nope a "pre tic" sensation is actually super common with all forms of tic disorders including functional

I almost always get a sensation before tics. To me, it feels almost the same as getting blood drawn for lab work - when they actually need more than a few drops. You're definitely not crazy. And even if no one else experienced this, you still wouldn't be. Being the only one doesn't invalidate your experience. Still, you're certainly not alone in this case.

Yeah I get that. It feels like someones pouring liquid on my back before I get back tics sometimes if I try and suppress them for too long