Well that was 11 years ago and I am still alive, so no tumor.And?????
Was having really bad bouts of vertigo, turns out it was just Meniere's disease.
Fun fact: there were moments when I couldn't even stand up without falling over but could ride my bike just fine. In fact during the 24 hours of Seven Springs one year I put in my fastest night lap in right after falling over several times walking through the start/finish area. I did get all wonky off a jump, world started spinning once I left the ground. Turns you you really don't use your sense of balance all that much while riding, feel and visual feedback.