 [ Symptoms ] can you fail a drug test from secondnhand marijuana smoke [ Disease ] dizzy spells and blackouts may be caused by a drop in blood pressure which temporarily reduces the supply of oxygen to the brain this may occur when getting up quickly from a lying or sitting position postural hypotension anaemia also may cause it but shaking and seizures may be due to low blood sugar or epilepsy … then you need to go for cbc and eeg