u/Kinsey525

Hi guys!
I purchased a sleepeezee Kennington mattress about 50 days ago and my girlfriend finds she wakes up with lower back pain recently. She has a small frame but big bum and believes the mattress is too firm and pushes back too much. Has anyone had the same issue? Does the mattress soften more? As the one in dreams we tried again today and it was way softer!
We are debating between adding a 5cm latex topper or returning to dreams.
Any advice is appreciated!