I wanted to know if you've had something like this, I am 39 weeks and …

I wanted to know if you've had something like this, I am 39 weeks and 3 days pregnant. For three nights now I haven't been able to sleep because my lower abdomen and waist are very painful at night, but during the day it's fine, it doesn't hurt so much. Yesterday I saw a doctor, she examined me on the chair, did an ultrasound (no contractions visible), and said there is some low amniotic fluid, but sent me home saying that everything is normal, there's no dilation and wait for contractions or when the water will drain, but I don't like how it hurts at night. I'm worried.