A soft tension matress

I would appreciate your advise. I am a 62 year old woman, suffering from arthritis of spine, with spondylitis . My neck, shoulders and hips are particularly prone to pain. I weigh 9 stone 4 and slim build but wide pelvis which make my lower spine particularly painful on a firm mattress. I have never yet found a mattress soft enough for me. I have stayed in friends houses, hotels, but most beds are too hard and I end up with painful shoulders and hips. I have done a lot of research and would not choose memory foam as night sweats are a problem for me. So, latex or deep springs/" title="pocket spring">pocket spring - help I,m confused. My arthritic bones are crying out for a lovely soft mattress which would accommodate them! Would be happy to spend up to £1,000 to get the right mattress. I have a slatted base and sleep alone so don't need to consider a partner. Many thanks.