Hi cewashko,
Unfortunately only you can feel what you feel on a mattress and there are too many unknowns, variables, and personal preferences involved for anyone to be able to suggest a specific mattress based on specs (either yours or a mattress), health conditions, individual circumstances, or “theory at a distance” (see mattress firmness/comfort levels in post #2 here) but there is more information about the different types of “symptoms” that people may experience on a mattress and some of the most likely reasons for them in post #2 here that can help you with the detective work that may be involved in identifying the most likely reasons for the “symptoms” you are experiencing.
Based on your comments and description though … if I had to guess I would say that it sounds like your mattress may be too soft and isn’t a suitable match for you in terms of PPP (Posture and alignment, Pressure relief, and Personal preferences).
If your mattress is too soft then there are some suggestions in post #4 here that may be helpful but in general terms a topper won’t be an effective solution because while a topper can help to soften a mattress that is too firm … the most effective way to firm up a mattress where the comfort layers are too thick/soft is by replacing them with thinner or firmer layers rather than adding a topper which will generally only have a partial or temporary effect (and in some cases can make things worse).
Are you able to exchange your mattress for a different one that would be a better “match” for you?
Phoenix