Hi blakeaf96,
There is more about hotel mattresses in post #3 here and the posts it links to. In most cases they are lower quality and more costly versions of similar consumer mattresses sold by major brands in retail stores.
These are just pictures of the outside of your mattress and they don’t provide any meaningful information about your mattress. It does look like there is some sagging in your mattress but a picture of the mattress lying flat on the floor with a straight edge (such as a yardstick or broom handle) over the sags would show this more clearly. If there are impressions in the mattress that are deeper than your warranty exclusions and there are no stains on your mattress of any type and your mattress is still under warranty then you may qualify for a warranty exchange.
If your mattress is too soft or has developed soft spots or is sagging (which is the most likely cause of back pain) then there are really no great or simple solutions to fix it but there are some suggestions in post #4 here that may be helpful on a partial or temporary basis.
Unfortunately your mattress most likely has some low quality materials in the pillowtop and comfort layers and outside of the previous suggestions which may provide some temporary or partial relief … after 6 years it has probably reached the end of its useful life.
Phoenix