Hi eeks,
While it’s not possible to “diagnose” mattress comfort issues on a forum with any certainty because they can be very complex and there are too many unique unknowns, variables, and complexities involved that can affect how each person sleeps on a mattress in terms of “comfort”, firmness, and PPP (Posture and alignment, Pressure relief, and your own Personal preferences) or any “symptoms” they experience … there is more 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.
Having said that … if I had to guess (and of course it would only be a guess) … based on your comments and feedback it sounds like your upper layers could be too firm so it may be worthwhile considering replacing your medium topper with a soft topper.
It’s also possible that your discomfort could also be a pillow issue because one of the most common causes for neck and shoulder issues is the pillow you are using. A suitable pillow is an essential part of good alignment for the head and neck and upper body and can reduce some of the pressure on your shoulders because the gap between the head and the mattress and the curve of the cervical spine needs to be supported just like all other parts of the spine. Like mattresses … there are certain “needs” that depend on body type and sleeping positions but with pillows, personal preferences play a more important role because the face is much more sensitive to textures, temperature, smells, and other more subjective “feel” based properties of a pillow. There is more about choosing pillows in the pillow thread here.
The most important suggestion I would have though would be to have a more detailed phone conversation with SleepEZ to ask them for their suggestions because with their knowledge about their own mattresses and their many years of experience with helping their customers they would be the most reliable source of guidance. A phone call is also a much more effective way to communicate more detailed and complex information and allows for real time interaction as well (see post #4 here).
The choice between memory foam and latex would be a preference choice rather than a “better/worse” choice and some people prefer the feel and slower response of memory foam and some people prefer the feel and more resilient response of latex. There is more about the pros and cons of latex vs memory foam in post #2 here but the best way to know which types of materials you tend to prefer would be based on your own personal experience.
Memory foam is also a softer material than medium firmness latex so again it may be worthwhile considering a softer latex topper first since this would be closer to the firmness level of memory foam (although it would still be a little firmer) unless of course you know that you prefer the feel and response of memory foam.
How a material feels when you push on it with your hands or sit on it can be very different from how it feels when you lie on it because when you lie on a mattress your weight is spread out over a much larger surface area which will change the “feel” and firmness considerably. Latex in general is a more “supportive” material than other types of foam such as polyfoam and memory foam because it has a higher compression modulus which means that it gets firmer faster than other types of foam as you sink into it more deeply so it can feel both soft or firm depending on how deeply you sink into it. When you are on your side there are more pressure points such as your hips and shoulders that need to be “allowed” to sink into the mattress more deeply so it’s not uncommon that a mattress that works well for back sleeping is too firm for side sleeping because side sleepers often need a softer top layer than back or stomach sleepers.
Phoenix