Pain in back

So im 33 weeks pregnant , i started externship on Monday and i have to do 40 hours a week basically 9-5 until i finish my 200 hours . My plan was : finish externship before having my baby on January 19, but now i have really bad lower back pain to the point I’m limping and it hurts when i try to walk normal . Im so sad rn . I started getting this pain after my first day of extern because the majority of the time I’m standing and walking and only sit when theres no patients.