My vein in my neck bulges out on left side of my neck and slightley right of neck when i lye down is it normal? when i get up it goes back in what's causing it should i see a doctor please tell me soon?

This can be simply an effect of gravity and your head position on the return of blood from your head/brain in your neck vein/jugular veins. Unless you are having shortness of breath or swelling of your feet, you don't likely need to seek a doctor urgently.

This is normal. When you lie down the pressure in your jugular vein is higher than when you are sitting or standing, so the vein is more prominent. This is especially visible in individuals who are relatively thin.