Hi berri2,
There is more about the typical odor of different types of latex and a link to some suggestions that may be helful in post #2 here.
It sounds like what you are smelling is the “normal” smell of Talalay latex which will dissipate to levels that most people won’t notice over time although since your topper was used it’s also possible that it could be something that was spilled onto the topper by the original owner.
Phoenix