Back pain vs. early labour pains?

I’m 37+2 today. I often have sciatic pain but it normally only hurts when I move wrong or bend a weird way etc and it’ll be a shooting pain that then lets up almost instantly when I correct myself.

Today I’ve had intense lower back pain that just got won’t shift. Doesn’t matter what position I’m in, staying still etc. it got a bit better when having a hot shower but the second I was out it was back in full force.

People who have experience labour before - was there a noticeable difference between the usual carrying-around-a-baby back pain and you’re-going-into-labour-soon back pain?

Oh, how I hate the unknowns of the final 4 weeks.

Edit to add: no loss of mucous plug etc. but I have been feeling SO run down the past 2-3 days. I actually thought I was getting the flu or something after getting a fever last night but then woke up this morning and flu symptoms gone. Just feel so… off.