What Causes Headache And Dizziness?

My mom has a history of stroke, hypertension, diabetes, high cholesterol, sarcodosis, and has has two stent placed in her heart some years ago. She has never had a heart attack and her last TIA was around 5 years ago. She had been doing pretty well for the most part. Trying to keep blood sugars and hypertension under control with meds. She was recently home sick for almost three weeks with bronchitis. And her first day out of the house after three weeks went pretty well. However when she layed down to sleep she felt dizzy, naseous, and vomitted about three times through out the night. We figured that it was something that she had eaten but since then (about 1 wk ago) she has not been able to lay on her left side without feeling dizzy and she has been complaining of minor, nagging, headaches. What could it possibly be?