if you have to struggle to keep you head down you messed up your swing somwhere along the line way before that point. here is a simple drill to truly understand what I am talking about
take practice swings and swing VERY outside in 3-4 times and notice what the head does, then swing VERY inside out and notice what the head does. What the head does in the golf swing should be way down on the list of things to think about, or off that list completely. head lifting up is usually caused by bad swing path, over the top, or a lunge.
try that little test and let me know what you found,