It seems that your son is having Chronic Kidney Disease
You need to consult your doctor to find out if the kidneys are irreversibly damaged.
If so then your son requires lifelong dialysis
or a renal transplant.
His serum creatinine
is going to increase till your next dialysis session.
From the reports it looks like he requires dialysis more frequently.
kidney failure patients develop low urine output over period of time as kidney function deteriorates.
Consult your Doc for proper medications