FOR A FEW YEARS I HAVE NOTICED MY RIGHT FOOT STARTING TO SLAP DOWN WHEN I WALK-IF I HIKE THERE IS A TIRING AND ACHING IN THE RIGHT GROIN AREA THE LONGER I WALK AND I ALMOST HAVE TO DRAG MY LEG AFTER A FEW MILES. IT DOESN'T CAUSE ANY PAIN WHILE WALKING EXCEPT WHEN THE GROIN STARTS TO TIRE. I HAVE TROUBLE LIFTING MY LEG UP TO WAIST HEIGHT WHILE STANDING. I WAS TESTED FOR MS AND THE TESTS WERE NEGATIVE. ANY THOUGHTS?