What Causes Altered Sense In Smell Followed By Dizziness,blackouts And Nausea?

for a few years now, i get relatively brief spells that consist of weird smells(i can't compare them to anything), followed by dizziness that almost and on occassion has led to blackouts, this is often accompanied by nausea, i am a 59 year old cancer surviver. if it's any help, when i've been taken to e.r. with this problem, often my blood work comes back showing i have zero potasium. any thoughts?