hello there and thanks for using this forum to pose your worry
the presence of stones in the kidney can cause reccurence of his pain as the stones move down the urinary tract
however, neither the kidney stones, nor the diverticulitis
is the cause of the back problem. rather, this is what we called a slipped disc
or discal hernia.
he might require good analgesia and stabilisation of his spine. surgery is also an option.
for sure, he is already treated from his diverticulitis and should now see a urologist
for the definitive management of the kidney stone, then a neurosurgeon/rheumatologist
for the back problem.
i wish him a very speady recovery. thanks