The guitarist was struck down with an agonising headache over the weekend (10-11Nov12) and he made an emergency medical appointment after a friend warned him it could be the sign of something more serious.
Poynter's doctor dismissed the star's fears and sent him away with painkillers.
He tells British newspaper The Sun, "One guy said it was a tumour but the doctor told me you don't get headaches from tumours. I've been suppressing it with (painkiller) Nurofen.
"I woke up the other morning, took some tablets and then threw them up 10 minutes later. Then I started to panic: 'Oh f**k, it's a tumour.'"