Hi BckyLTylr,
I don’t know if you are an exclusive stomach sleeper (which is very uncommon) but in very general terms stomach sleeping is the most risky of all the sleeping positions in terms of alignment and will usually need either thinner comfort layers and/or firmer comfort layers or in some cases a firmer support core to help prevent their pelvis from sinking into the mattress too far and sleeping in a swayback position which can certainly lead to lower back pain.
If you sleep close to your husband then it’s also possible that you are partly sleeping in the impression that he creates in the mattress as well (which would be deeper than yours if he is heavier than you).
It’s also very common that stomach sleepers need to sleep with a thin pillow under their pelvis/lower abdomen to help prevent this.
Some of the suggestions in post #4 here may be helpful as well.
Phoenix