I have been on Concerta 27mg for a year and about one week ago I switched to Concerta 18mg. Since then, I have had severe dizziness daily. I get it mostly when walking, or when in a moving car or bus. It's horrible. I'm afraid to even get in a car now because I know I will be dizzy for hours after. Anyone else had this problem? My doctor said my dizziness may be from anxiety, not concerta. But My anxiety is caused by the dizziness! Please help!