What Is The Treatment For Dizziness , Nausea And Numbness In The Left Side Of The Body?

i have been having dizzy/nautious with some visual changes during short episodes that are becoming more frequent. I have high blood pressure and a low functioning thyroid in which i was taking meds for, but stopped to see if the cause was my meds. I am overweight, and have had chest pains along with numbness in the left side of my body. What could be the cause?