Exactly what happens to me. This once happened to me once where I was dreaming I was in class, at 7th period and I felt a light throb in my head. 3 years later, this was happening. I recognized the dream si far in reality, remembered the teacher's words and anticipated a throb. Instead, I felt a sharp pain in my head and blankly stared at the walls for the next 3 minutes. This happens to me a lot. Don't get me going on my weirdest dream though.