If echo, stress, ekg and x-ray come back clear, what are the chances of having coronary artery spasms& would the studies have shown a presence ?

Probably not: Coronary spasm occurs both in patients with blockages as well as in patients without (the classic prinzemetals angina description). Most tests would not show it unless a provoking factor was stimulated or initiated (example ergonovine). It's often made as a diagnosis only after witnessing spasm or ischemia under provocation after anatomically defining the extent of coronary disease.