Prenatal kidney enlargement. On its own?

Hi my wife name is meenakshi SAXENA age 32 y female She completed 20 week of pregnancy, and she had an level 2 ultrasound and quadruple marker blood tests .  Here kidney size of baby were 4.2 and 4.4 mm (date 29/07/20). Rest all parameter in ultrasound and quadruple test reports are normal. Also amniotic fluid normal. Now for 2 days she is experiencing pain in left lower abdomen which increases when she lying taking left side . It's continous since 2 days . We worried and ask go for an ultrasound where anything serious ruled out but the both kidney size of baby are 4.6 and 4.8 mm. (07/08/20). Also amniotic fluid adequate. Now we are worried what to do in this situation. Can it be dangerous for our baby. And how long will it be heal on its own ? Plz help.