@kingrollo As someone who myself has back issues caused by illness and abdominal operations, your question is too vague and without detail to get the answers you need. In reality, you’ll only get personal opinions that suited that persons circumstances (Including mine!)
Your back issues. Are they muscular or skeletal? Are they through injury?
Are you a back, side or front sleeper?
Lots of other questions around single/double bed, pillows, sprung base, divan etc
What is your physio suggesting?
You need to be clear on the problem you are trying to solve and then work through the components