Vertigo can feel like dizzy, or it can feel like whirling or spinning. I am usually lying down when it hits and it may sound funny to say, but it can sort of feel like you are falling too. To sleep, I had to lay inclined, which can cause a bit of a sore neck. At first, I thought it might be a withdrawal from pain meds. It kept happening, though, which lead me to seek medical advice. I am three years out from radiation and in my case, the vertigo has gotten less often.