Something interesting I thought may help: my uncle suffers from something called TMJ, it can be mild or severe, it's very common in mild cases. It's basically mild problems with either jaw joint and the surrounding tissue but the effects can be quite severe, dizziness, headaches, head pressure. I mention this because I remember reading a while ago about many 90s ravers now having jaw problems from the frequent gurning! If your jaw clicks or pops a lot when you move it or you have an obvious underbite / overbite then it's worth looking into. It also seems to be one of the most affected places from muscle tension associated with severe anxiety.