Leg pain worsen at night time. Problem?

Asking for my wife,3 years ago she had C-Section for my first baby. When my child was six month old, she felt leg pain (from knee to foot) at night time. Due to feeding,we are not consult with any doctor. After one year, We went to consult nuero specalist and he just checking and referred to some diagnosis like Rheumatic arthists and some blood testing. We dont have any issue in report. 1 year ago,we went to consult one more neuro doctor, He examined staright walking on line in the floor, tongue rotating. Not find any difficults. My concern here is, Why still she is feeling leg pain at night time. She is ok at morning, but night strecth and shaking her foots till she sleep. we are planning for next baby. So please clarify me, It is seviour problem?