Salt and preservatives messes with *everybody's* body.... it's just that some people are "used to it."
I tell ya'... if I ate what the normal population ate, I would be writhing on the floor, incapacitated. Unfortunately, I cannot partake, as I have a strict (and boring) diet.
Your body obviously is sensitive, and is guiding you to *choose* the "good diet."
However, if it EVER happens (your shoulder blade, pain, etc.) starts to happen while you are eating GOOD, then you will definitely want to get it checked out.
I'll tell you right now... I think what you have is going to turn into a problem. But I'm not going to be all nelly-negative right now, let's just say: eat a perfect diet, and pay attention to your body.