Mattress advise for bad back

Hi. For the last 7 years I have been sleeping on a memory foam mattress. I am now suffering with severe lower back pain (not caused by the mattress though now not helped). I am 8.5 stone in weight and 5’1” in height; I am also now waking every morning in cold sweats so need something that helps with temperature control. Could you please suggest a mattress that would be a suitable replacement? I sleep alone and have a slatted double bed. Many thanks, yours painfully. Su