Hi ssum,
I switched your post to a new topic of your own so it wouldn’t get mixed in with another member’s topic.
It’s certainly possible that your friend’s mattress is too soft for you but if it was then an additional soft topper (which sounds like an egg crate polyfoam topper which would typically be very soft) would be more likely to make it even softer and could make your “symptoms” worse so your experience with the topper improving your “symptoms” seems to contradict your suggestion that the mattress was too soft.
If you have only been sleeping on your mattress for a few days then it would generally be much too early to really assess whether your mattress needs any changes at all since your mattress will need some time to break in and you will also go through an initial adjustment period with any new mattress or sleeping surface and it’s usually best hold off on making any changes to a mattress for at least the first few weeks. Some of the suggestions in post #2 here may be helpful while you are going through the initial break in and adjustment period.
While I can’t feel what you feel or see you sleeping on the mattress … if it does turn out that your mattress needs some fine tuning then post #2 here and the posts it links to has more information about the more common “symptoms” that people can experience on a mattress and some of the most likely reasons for them that can help with the detective work and trial and error that may be involved in deciding on the types of changes that would be the most helpful.
Post #2 here and post #4 here also has more information about primary or “deep” support and secondary or “surface” support and their relationship to each other and to firmness and pressure relief and the “roles” of different layers in a mattress that may also be helpful in clarifying the reasons for your symptoms as well.
The BIAB Coolrest is 100% natural continuous pour Dunlop made by Mountaintop foam. It would be very comparable in firmness to 100% natural molded Dunlop that is in the same density range but Mountaintop Foam uses two different methods of rating the ILD of their latex and their ILD numbers don’t compare well to the ILD numbers for other types of latex (either 100% natural molded Dunlop or Talalay). There is more about the different types and blends of latex in post #6 here.
Spindle Mattress is a member of this site and they use the same type and blend of latex in their mattresses and Neal there would probably be the best source of information and guidance I know about comparing the different firmness levels of Mountaintop continuous pour latex to other types of latex.
Phoenix