Susan...
while I don't have your DX conditon, I empathize with much you're experiencing.

Finding comfort esp in bed has been very challenging. I tried many toppers, cushions, etc. then I bought a new memory foam mattress-- hoping comfort and sleep would improve but still "too hard" and uncomforatable --seems to exaccerbate pain & other neuro SX. .

I began to use [medical] sheepskins in bed --first for cold feet then placed under-most sensitive or painful sites (like my knee when it was fractured few weeks ago)
Sheepskin has helped more than anything I've tried but size of skins can be limiting as well as shapes. I"ve been re-consdering getting sheepskin "topper' matress- cover for entire mattress. pricey but something to consider???

my mother went thru similar weight loss & comfort problems.as well as wounds . tried various mattresses--foam, water, etc; sand beds and some other things ordered by DRs & therapists were covered by Medicare. (sorry I don't recall all -or know what may be available now for you. Perhaps a consult w/ DR or PT or other therapist -- could be beneficial.
or others will reply with better suggestions-- somethings that will help ---
wishing you the Best....