Having cross dominance might affect your head.  Are you talking about a foggy feeling inside your head?  I often find cross dominance coinciding with dyslexia.  However, if your head just feels heavy, then it would not be cross dominance.  If you have epilepsy and are on medications, then this could also be the cause of your heavy head.  I would talk to your doctor to get a clearer picture about what is going on before I did anything else.