Mattress topper choice

I have degenerative discs in my lumber & cervical region & suffer chronic pain in my spine & pain in both legs. I bought a Tempur mattress years ago & although it was a dream to sleep on & gave great support, it held the heat from your body so was far too hot to sleep on & heat causes my discs to swell which creates more pain. I replaced it with a natural fibre mattress thinking it would solve the problem but although I bought a soft one it's far too firm still, I need to be able to sink into the mattress like I did with the Tempur which moulds to your body. I have been told a latex topper would have the softness & support like the Tempur but being a natural material it would not hold the heat from my body. I need it to be as soft & supportive. & mould to my body as the Tempur did. Please can you help advise me what topper would be suitable. I desperately need to be able to sleep without all this pain from a hard uncomfortable mattress.