What Causes Pain In Right Arm From Shoulders To Wrist?

Yesterday I had the worst pain in my right arm from shoulders down to my wrist. This morning, pain is still there just now as bad. I felt ok when I got up but within the hour I threw up and have thrown up no matter what I try to eat or drink. Last thing I tried was a coke and saltine crackers. I have no warning to get to bathroom just throw up and hope to get it in trash can. I'm also feeling light headed. What could it be?