My son is two years old and he has both feet swollen. The Swelling has gone down compared to the first day,but what seems weird is he will be fine for a couple of minutes and then out of the blue he will complain his feet hurt again to the point he doesn't want to walk on them. Can some one please help me what should I do and how can I help him?

Optional Information:
Male , Age: 2

Already Tried:
we took him to the doctor had a urine test done and blood work because grandpa has cystic kidney disease