Went to get bloodtest and the needle hits a nerve and pain went thru my arm. she then reshot me on another vein. is this suppose to happen?

No, but it can: Nerves and veins can be very close to each other; sometimes, veins can be hard to find (small or deep or hidden by fat, etc.). Uncommonly the above problem can occur.

Arm Veins.: When having blood drawn from an arm vein sometimes the person drawing the blood may miss the vein requiring a second attempt. There is always a chance that the needle could also hit a nerve. Fortunately this does not occur frequently and your arm should improve over about 10 days.