need advice on my dogs paw

hi! so i don’t even know what group to post this in, i have a pitbull mixed with lab. she’s about 5. i adopted her a couple years ago and her paws always look so rough.

i’ve used vaseline, doggie paw pad lotion, taking her to the vet and they sanded it off and told me to apply vaseline everyday and i do but they always come back looking like this?

her paws are just so dry and rough and they crack constantly which is so painful for her. she’s so sweet and i need advice but all the vets do is sand it and tell me to just bring her back every couple weeks but it’s so expensive! 150 everytime plus the meds after.

her names mary puppins btw