Is Nitroglycerin Effective For Stomach Pain?

I have been having arm heaviness and aching and in my shoulders. I saw a cardiologist yesterday and had a normal ekg. However, he is running tests . He prescribed nitroglycerin tablets. My question is this: If these pains are really stomach related will nitroglycerin still get rid of the pain. The instructions say to take every 5 minutes times 3 if needed then go to ER. I am a 57 year old female .