What Causes Dizziness And Weakness?

My grandmother feels weak and dizzy every morning. She is not a diabetic. We have taken her to the hospital four times. I had them take her off her lisinopril for fainting. She is on ASA,MVI,Metoprolol ER,Prevacid,Evista,Levothyroxine,statin,recently put on celexa and sinemet(for shaking). I think parkinsons or other medication causing problems. I asked for a holter monitor. They ran every test available(EEG,CT,ECHO,TILT TEST,ALL LABS,A1C AND ENDOCRINE(ALSO PER MY REQUEST). Then the rest of the day she is fine.