Thanks for the heads up. I called and they told me that they had “lost the patent” but that they were working on something similar that may be available in a few months so I’ve added a note to the post I linked.
A pillow can certainly be a common cause of upper body “symptoms” (see post #2 here) and a change in mattress that sinks in more or less than your old one can affect the distance between your head and neck and the mattress and change your alignment so a new pillow that can compensate for this is often necessary. Pillows are much more of a preference issue than a mattress and it can take some trial and error to find the “perfect pillow” (if such a thing even exists :)) but the pillow thread here may also be helpful.
I think that’s a very wise approach so you can identify the effect of each change you make … and I would also give each change a few days at least so you can have more confidence that any changes you experience aren’t an anomaly or exception.