I have had a couple separate episodes of sudden nausea and vomiting. Both times it has been at the end of the day around 9pm. In both cases, I was fine all day and then in the evening I felt nauseous and vomited. The nausea has lasted several hours and then goes away. This happened again last night. By morning it had gone away and I was fine during the day except for feeling extra tired and bit "off". Then tonight I'm nauseous again. Any thoughts?