Toy poodle renal failure stable BUN and CREA but eat dirt constantly

[duke167]

13 years toy poodle, sent to vet hospital in March 2016, stayed there for more than a week for continuous fluid injection and medication, at that time he was diagnosed with renal failure stage 4 and pancreas infection.

Apr 2016:
UREA 26.1 mmol/L (was 34.1)
CREA 265 umol/L (was 2.72)
BUN/CREA 24
PHOS 3.83 mmol/L

Apr 2017:
BUN 33 mg/dL
CREA 3.0 mg/dL
BUN/CREA 11
PHOS 5.1 mg/dL

During the last 12 months, we feed him purely K/D (can) twice a day, my dog usually finish all of them.
We started from daily IV, then every other day, then 2 times a week, then once a week.
He behave just like a normal dog, beside he wee wee a lot and randomly around the house.

now questions:
- he eat dirt constantly since 2-3 months ago, he even ate the tiny plastic toy which he never did before. Is he feel hungry or lack of certain vitamins?
- his poo poo was always moist and sticky since he was on K/D, and more like diarrhea in last 2 weeks, is it a by-product of K/D? should we consider to feed him other food?
- Does IV really help him in this stage? I really want to avoid needle him