Angina

[Mamacat104]

I have been experiencing chest pain in the center of my chest when I walk. I have had a stress test where they do the echocardiogram before you walk really fast on the treadmill and again afterwards. My stress test was fine. I went 9 min on the treadmill with no problems. He said it looked good. I have had a Body scan where they scanned the lungs and heart and it showed no calcium build up in the arteries...supposed to all be clear. Lungs looked okay also.
I can work in the yard, hauling mulch, digging holes for plants and all that and no problem with the chest pain I can work out with the Wii for an hour doing the Hula hoop, boxing and then running in place for 10 min and I'm okay. But when I get outside and my neighbors and I start walking at a good pace (not fast...but not just strolling along), it starts to hurt. But by the time we have gone half the walk, I'm breathing better and the pain is gone...Now and then I'll feel a twinge after that, but for the most part the pain goes away.
The doctor gave me some Angina meds, Diltiazem, which didn't do anything to help...it still hurt when I walked part of the walk and now and then it would hurt just walking to another room and would subside quick as I sat down. He then gave me Ranexa. After taking Ranexa for about 3 days, the pain was constant all day long. I stopped taking the Ranexa and now the pain is only now and then during the day and when I walk, it hurts for the first half of the walk, but not while I work out in the house before the walk.
Any idea what could be the cause of this kind of pain...It has been like this for almost a year now....I don't let the pain slow me down, I keep going, but it is aggravating dealing with this pain all the time and just really not sure what it can be.
thanks
Barbara