Hi justjeannie,
Unfortunately I can’t feel what you feel or see you on the mattress and I don’t have enough information about you or either mattress you tried to be able to guess what may be happening or the reasons behind your experience. Trying to “diagnose” the reasons for any particular person’s back pain or discomfort on a forum would be much like a doctor trying to diagnose any health issue with very limited information and without being able to see you or assess you in person and in most cases with these types of situations I am mostly dependent on the information that you provide about whether you think your mattress is too soft or too firm or “how” it is too soft or too firm (in the comfort layers or in the support layers).
It would also be helpful to have a reference point of a mattress that you have slept well on in the past (with as much specific details as possible) and since I’m not familiar with either mattress and I don’t know the specifics of the materials and components in each of them it would also be helpful if you could provide more specific information about each of them as well (see this article) which may also provide some additional insights into the reasons for your “symptoms” and experience.
Having said that … I can link you to more information that may help with some of the detective work that may be necessary to try and figure out the reasons for the symptoms you are experiencing.
Each person can have different reasons for very similar symptoms so the first step would be to decide on whether you believe your mattress is too soft or too firm. Post #2 here may be helpful if you believe your mattress is too firm and post #4 here may be helpful if you believe your mattress is too soft. If you aren’t sure then post #2 here and the posts it links has more information about the most common symptoms on a mattress that may help with the detective work that may be necessary to identify the underlying cause or causes behind what you are experiencing.
I also don’t know how long you slept on either mattress but if it’s less than a few weeks then the best idea may be to “do nothing” at first so that your mattress has a chance to break in and you have a chance to adjust to a new sleeping surface. The posts I linked include some “non mattress” suggestions and one of the most common reasons for upper body symptoms are a pillow issue so it may be worth experimenting with a different pillow to see how it affects your symptoms as well.
The first step though outside of the non mattress suggestions would be to provide as much detail as you can about your mattresses and any additional details that you can about your experience on each of them which may help me to make some “educated guesses” about the types of changes that may be helpful and whether your symptoms are pressure related or alignment related (which is probably more likely).
Phoenix