What Causes Sudden Black Outs When Diagnosed With An Ear Infection?

My mom is in the hospital and the dr.s have ran a bunch of tests. MRI, EKG.... the problem she is having is she just passes out for a few minutes then wakes up. Sometimes she is fine others time when she wakes she can t walk. The most resent was she was trying to eat, they brought her applesauce and cereal. She took a few bites of the cereal, fell asleep and when she woke she couldn t talk and had slight movement of her tongue. She has electrodes attached to her head. They have determined that she has no blood pressure change what so ever and no neurological changes.... what could be causing this.. could it be vertical? She has no nausea. But did have an inner ear infection about 2 weeks ago.