Yeah a common cause of this can be malnutrition.... Google your bodies average daily nutritional needs and do the math whether or not your living healthy.
Yea, it's not because you're not getting your daily dose of THC. There is more than likely an underlying health issue causing the nausea. Marijuana just hides the symptoms of nausea.
NAUSEAAAAAAAAAAAAAA!!!! [ame=http://www.youtube.com/watch?v=50FG2C_g_DQ]At The Gates - Nausea - YouTube[/ame]