Still having pain after tests rule out CAD?

1 month ago I had a cardiac cathaterization to rule out coronary artery disease. I had no blockages whatso ever. I am still having the pain in the center of my chest, and the 'lump in throat' feeling. My b/p is normally low 110/60 and this feeling happens both at rest & during excercise. Even though CAD and angina were ruled out a month ago, is it possible for that to have changed?