Hello... My Grandmother Has Swelling In Her Legs (above Knees

Hello... My grandmother has swelling in her legs (above knees to her feet) its painful walking and standing on them (more than normal...she's 91 & quite active) she has cramps and spasms in her legs (more than normal as she does have neuropothy in both legs) also when in a prone relaxed position her muscles... Such as calf muscle) remain ridgid. There is also stiffness.... She does have heart problems... Which means she is on a low salt diet...I also verified she is NOT having pain near her kidneys... Any suggestions on what it could be? Her doctor appt is Monday