Can this happen? I’ve been so tired lately and I have an appointment with a sleep specialist for possible narcolepsy. I’ve been yawning constantly for months now. Today at the vets office of all places, my jaw locked open. I freaked but I was able to get it unstuck. Now my jaw just feels all weird. I also increased my lamictal on Tuesday so I’m wondering if this is a side effect. But should I be concerned about this?