Lower back pain

I am 19 weeks and for the last week or so I have had really bad lower back pain. I work at a daycare with twelve 4 year olds. I only work six hours a day. However when I come home and finally sit down (I maybe so for an hour at work) my lower back kills me. It's so bad that my husband sometimes has to help me up and I can only walk with my knees a little bent. My next appointment isn't until July 5th, so I was wondering what I should/what I can do about this. Thank you!