Hi jleb,
I’m sorry to hear that your mattress purchase hasn’t turned out as well as you hoped for (at least so far).
There is more detailed information about the most common symptoms that people may experience when they sleep on a mattress and the most likely (although not the only) reasons for them in post #2 here.
There is more about primary or “deep” support and secondary or “surface” support and their relationship to firmness and pressure relief and the “roles” of different layers in a mattress in post #2 here and in post #4 here that may also be helpful in clarifying the difference between “support” and “pressure relief” and “feel”.
These posts are the “tools” that can help with the analysis, detective work, or trial and error that may be necessary to help you learn your body’s language and “translate” what your body is trying to tell you so you can make the types of changes or additions to your mattress that have the best chance of reducing or eliminating any “symptoms” you are experiencing or decide whether to replace or exchange your mattress.
Your Chiropractor friend is right that one of the most common causes of upper body “symptoms” is a pillow issue.
They are also right that there is a break in and adjustment period for any new mattress as well and for some people or some mattresses it can be a little longer than for others (see post #3 here).
If your symptoms don’t resolve themselves over the course of the next week or two with changing pillows then it would certainly be worthwhile testing the zoned support core to see how your sleeping experience changes.
Phoenix