Sleeping in a bowl of foam, painful for herniated/art disc.

I sleep from 1:30am till my back aches at 2-3:30am then I wake up, have to put my pillow at foot end then back to bed and sleep for another 3hours. My legs don't weigh down the mattress like my torso does. So normal foot end still keeps support better than where my torso was laying. Normal position on mattress compresses discs in my lower back causing more pain. So eventually torso has no support from mattress. Mattress needs firmer support to RETAIN SHAPE UNDER PRESSURE to maintain straight back position to prevent ongoing compression of spine from lack of supporting mattress. However, needing pillow top of sorts for reducing hip pressure points. I suffer from arthritis between L3-4 and bursitis in hips