Hi, I Am A 51 Year Old Male. I Have

Hi, I am a 51 year old male. I have had a previous brain tumor as well as 2 strokes. I awoke from a sound sleep 8 weeks ago with a terrible headache went to the emergency room. Had a cat scan and lumbar puncture they found nothing. The headaches continue with bouts of vomiting. Had an MRI and have been seeing a neurologist he is unable to determine the cause.