I had pain in my lower back until I bought a knee pillow. Found it online of course. In addition when I do need to sleep on my back, because of a sinus issue

I had pain in my lower back until I bought a knee pillow. Found it online of course. In addition when I do need to sleep on my back, because of a sinus issue (allergies), if I raise my feet and my head it helps. A few years ago my wife convinced me to buy one of those beds where you can raise the foot or head. We paid WAY too much for it, I later found cheaper ones online. But I must say I am grateful my wife convinced me to buy it.