35wks + 5 .. excruciating back pain

I am experiencing this intense lower back pain & its very hard for me to walk or move because the pain is unbearable.. the pain causes me to flinch if i walk in a wrong footing & this is sudden! I woke up yesterday to this pain! I think it might be trapped nerve or muscle pull but walking and getting up has become a chore. I also think maybe cause my legs can't carry my weight anymore as my belly is huge & getting heavy or as my baby is getting lower now, it triggers an old injury (i fell during my 5th month) but the pain is !@#$% .. is this normal for late stage pregnancy?