What Causes Shortness Of Breath Upon Climbing The Stairs?

what can cause heavy breathing after not very strenuous activities such as going up one flight of stairs, walking a few steps from my bed to the clothes in the morning, getting up from the chair and walking,etc.--none of this has been happening all the time (e.g. during the three days this has been happening, I went to zumba, took two 4-mile brisk walks without huffing and puffing). Also, nausea (not all the time, but at various times during the day). High blood pressure when I just today saw prompt care dr (185/85--mine has always been low; it got down to 155/80 by the end of the visit). A feeling of anxiety whenever the nausea appeared and also a feeling of need for BM--looser stools. At times a feeling of kind of something sitting at the pit of my stomach. Could my reflux be causing this? Could I have blocked arteries? An EKG, chest x-ray, CDC, coagulation test, metabolic panel are all OK, except for a lightly low sodium and slightly lower kidney function.