How do I get my girlfriend to knock off this annoying habit?

My girlfriend Nia and I have been together for 8 months now. We’ve had ups and downs like every relationship, but it’s been a good time overall. The problem I’m having with her is a recurring, random thing she does. It’s so random and out of nowhere, but she whips her arms and legs around really fast, kind of like a bird when it’s molting. It’s not a full body convulsion, but her limbs and hands flail really fast. <br><br>The first time I remember being witness to this, Nia was making dinner for us while I played video games nearby. I don’t remember it exactly, but it was a few months ago when she did it the first time. I remember because I was shocked she hadn’t done it around me before then, after all we’d been intimate and spent an entire weekend alone together at a cabin in the woods. <br><br>I remember asking her what she was doing, and she seemed embarrassed. She pointed to a large roach on the ground near her feet, and I will say I’m glad I was there to kill it. But after that I started noticing it more. She would do that movement before bed sometimes, or in the morning, or sometimes when she was eating. I’ve asked her about it a couple times, but she says she just has restless legs. I’ve tried to get her to work on it, partly because it creeps me out and partly because it seems like she might hurt herself. She’s also already damaged a water glass and the sheets, and I’m afraid to let her use my car. I’ve asked her to get a doctor’s opinion on it, but she refuses. I’m starting to wonder if she’s demon possessed, but I don’t really believe in that stuff. I don’t know what else to do.