its happening, since the past two days, i think it happens when my heart rate increases, but it also happens when i laugh. its at the back of my head and when i workout, the pain is very bad at the back of my head, like my skull is getting crushed. I have low blood pressure and have suffered from head rushes, but this is very new. i haven't had any sort of head injury so its not a concussion. My mum hasn't mentioned going to see a doctor.... just hoping its not something drastic likes a tumour !!! :/