Singulair tablets are usually meant to be taken at night due to the side effects of drowsiness
. Occasionally the drowsiness could relate to a feeling of dizziness, but not vomiting unless you had exceeded the dose.
Singulair itself is unlikely to be effective for pollen allergy
unless you combine with an antihistamine like fexofenadine
There is no special diet for pollen allergy; but addition of a nasal spray
will help with the symptoms of rhinitis (sneezing, runny nose, white discharge, blockage).