Sounds like sciatica a bit. Regardless, go see a massage therapist certified in prenatal massage if you can. (I'm a prenatal massage therapist) Usually my clients report their symptoms go away for about a week or two after I see them. Make sure you are lying on your left side with pillows between your knees and feet, so that your hip, knee and ankle are all at the same height while you are sleeping. Also, yoga is wonderful- the cat stretch is great and will provide you with some relief. A good chiropractor would help, too! If cost is a factor- talk to your Dr. or Midwife, usually they can write a referral and then you can get it covered by insurance.
Also, instead of sitting on a chair for long periods of time, go get an exercise or birthing ball and sit on one of those.