swollen vulva in the third trimester

I noticed in the shower this morning that my vulva is very swollen, only 33 weeks along so I found it very alarming, I had my daughter at 34 weeks (8 years ago) but was really hoping to make it to term with this babe, could this be an indication of another preterm labor & delivery? Last night I also had quite a bit of lower back pain, but once I laid down it got better so I didn't think much more of it! Are any of you ladies experiencing some swelling of your lady parts?