Hi fridadc.
In a nutshell, anything is possible… there are people with different health conditions such as fibromyalgia that have a high level of sensitivity that can lead to discomfort and pain on just about any surface no matter how soft. In your case, as you mention that your alignment is good, then your pain seems to be more position related and depending on your preferences and sensitiveness, finding the right combination of materials and construction is relative and very subjective and it is as much an art as a science. It also is a bit unusual to experience abdominal pain when lying on your back unless you have some preexisting conditions that would surface when you are in this posture…if anything, normally the plushness and sinking a little deeper when you are on your back, would generally relax the abdominal muscles. As Jeff pointed out you may need to find out if the pain is not radiating or “triggered” from somewhere else within your body and some detective work may be necessary for you to identify the source of any pain or discomfort before you make a purchase.
Generally, there are different types of firmness and softness that different people may be sensitive to that can affect how they experience a mattress which are included in post #15 here.
I know that I pointed to some of these readings but, just in case I’ll list again some of the forum posts that talk about fine-tuning a mattress that may help you recognize or “diagnose” the underlying cause of different types of “symptoms”, pain, or discomfort that may be connected to a mattress.
[indent] Post #2 (this is the primary reference post for different “symptoms” that people may experience when they sleep on a mattress)
Post #45 (this is particularly worth reading as well)
Post #2
Post #6
Post #6
Post #4
Post #7
Post #7
Post #18 [/indent]
If all else is checks out good, then if I had to guess based on your comment that the problem seems to be limited to your back sleeping then I would say that the comfort layer is a little too thick (or too soft for back sleeping)
I am glad that you reached out to Jeff (our expert here) as he knows much more about sleep ergonomics, than most of the people I know (including myself) and I would follow his suggestions and keep away from adding more comfort layers but experiment instead with some combinations of materials in a mattress manufacturing facility and use the advice of the manufacturer themselves. There is not much more that either I or Jeff could add to this unless you gather some more data points to add to the picture.
Phoenix