Sudden onset of n/v/d x 1. then next day headache and thin yellow nasal drainage from one nostril. continued nausea and abd pain. no v/d.

Virus , bacterial : The initial nausea and vomiting are related to a virus. The yellow drainage represents a bacterial issue as nasal secretions should be clear or light green. I would contact you primary care provider to get an antibiotic if the yellow drainage continues. Drink plenty of water and stay hydrated. Try an antiacid to see if you can get the stomach settled. Good luck.