Some of us cannot control secondary behaviors like grimacing in the moment and crowd cannot control their own anxious facial expressions when they don't know how to react. You just gotta keep going. But do let them know what you have and how to react. That you get blocks and what blocks are. And that you want to finish your sentences unlike some presenters who pause intentionally and raise eyebrows to signal crowd to guess. If your boss allows, record yourself live so you can review what anxiety does to your body langauge and what kind of secondary behaviors you have. This will help you adjust your disclosure next time. I reviewed my recording and saw my eyebrows doing frowning and raising. So when I present, I let them know that when my eyebrows do that, my brain is just loading up next words.