I've Been Having Lack Of Appetite, Nausea, And Projectile Vomiting

I've been having lack of appetite, nausea, and projectile vomiting for a few days. I feel very depleted. When I lie down my stomach gurgles unpleasantly. I've had very little to eat and can barely keep liquids down (only in small quantities). My muscles are cramping and I feel weak in the knees.