Writing for my sister ... She is 63 yrs old, has COPD, High Blood pressure (she s on medication for that), and had a pacemaker put in a couple of months ago - tests revealed hear heart rate was all over the map before the installation. Since, it seems consistent. The current problem: 2 weeks ago she worked, training dogs outside in heat walking and standing all day, no problem. Then suddenly last week, she had chills without fever, and has no energy whatsoever. Says she can t walk 60 feet without needing to rest. That her legs feel like they weigh 500 lbs. She went to an emergency clinic (she was on vacation), and they could find nothing wrong, other than kidney function seemed a bit low and slightly dehydrated. Symptoms have now lasted more than a week. Any suggestions?