Motion sickness

Experienced motion sickness during my 600 meter swim Monday. Pushed thru another 300 meters and called it a night. Felt extremely nauseous with migraine. This was the first time I wore a swim cap and have a feeling I trapped water in my ears causing the sickness. I will find out if that is the case Wednesday. Tonight I worked back and rode stationary bike for an hour. Sunday I ran 7 miles to account for last weeks long run.