I love, love, love these ... had them for 3+ years and they have yet to flatten. So. Very. Comfy.
Beckham Hotel Collection Bed... https://www.amazon.com/dp/B01LYNW421?ref=ppx_pop_mob_ap_share
Currently 40% off right now if you clip the coupon. I also use these myself.
Everlasting Comfort mattress and pillow protectors
Beckham Hotel Collection Gel Pillows
A lot of my guests ask about the Beckham pillows during their stays. Middle of the road on price, they're comfortable, breathe well, and durable. After trying several different products, I landed on the pillow/mattress protectors linked above. They do an excellent job at protection.
So I got these from a recommendation from some people. I also got my mom hooked on them. So, I stack these (they are easy reshape and fluff):
Beckham Hotel Collection Bed... https://www.amazon.com/dp/B01LYNW421?ref=ppx_pop_mob_ap_share
I also have this wedge, not only is there a gap between my headboard and mattress, it also helps with getting my pillows right
VEKKIA King Size Bed Wedge... https://www.amazon.com/dp/B08Y198S4Q?ref=ppx_pop_mob_ap_share
I also sleep with a pillow between my legs to help alleviate stress on my back/hips. Just wanted to mention since you mentioned back pain. My regular pillows I use are these: Pillow