Dear gaurav Gupta,
Getting dizzy when you bend over is called orthostatic changes. It is most common to have dizzyness, orhtostatically while standing from a sitting or lying down positon.
You symptoms, however occur when you are in the "pike" position.
I would suspect that this is related to your stroke condition of 2 years ago.
One such development could be a syndrome referred to as BPPV, but there could be others.
If this condition is persistent, please seek the care of your phycisian, so that he can differentiate the cause, and provide proper treatment.
YOUR PAYMENT AND BONUS IF ANY MAY BE TAX DEDUCTIBLE

Edward M. Johnson