Last Monday, My Mom (age 64) Had A Nose Bleed.

Last Monday, my mom (age 64) had a nose bleed. On Tuesday she became dizzy and started loosing her balance and vision. Has had problems with vertigo in the past. Has made three trips to the dr including and ENT. She is taking an antibiotic. She can't focus her vision enough to walk. The dr tried the vertigo exercises with no relief. The only answer has been given at this point is maybe she has an infection that may last as long as three weeks. The dr is trying to get an MRI approved to rule out a tumor. Thyroid counts were "a little off". She has been confined to the bed for seven days now. What questions should we be asking? What other possible conditions should she be tested for? Thank you!