Hello,Im not positive but i am experiencing the same problem,I just went to have a heart test done and had my Carotid artieries Checked for a possible blockage,I would get to a Heart Doctor as soon as possible,im not sure in my case as i had already been told I have cardiomyapathy,which is an enlarged heart,your heart Muscle dosent fully pump out all of the blood from your heart,that is caused by a weakened Heart Muscle,I also was told in the past along with this Heart issue in 2003 that  in 07 while at VA Hosp.they did an ultra sound on my carotid arteries and I have a sligh Carotid Disease,I would not mess around with this,as i also was told in 03 of having a possib lmild heart attack,so I would get to a Heart Doctor ASAP and have Him order testings,to actually find out what  is going on.Jim