I'm not pregnant but I've had multiple back surgeries and a lumbar fusion. I find that the arthritis heating pads (warm moist heat) help and so does acupuncture. The acupuncture is very relaxing also and they can usually work on more than one problem at a time. I go twice a week and have had a very positive experience. The pain you feel down your leg is probably sciatica. I would give these options a try they don't contain and medication.
I go to a chiropractor, he's a lifesaver. my back and leg pain was so bad I could hardly walk. I literally was considering using a cane. I was about 23 wks when I started going. I went twice a week for three weeks, then once a week for two weeks and now i go once every two weeks for upkeep until after I give birth. I could walk normal within the first three weeks.
Some people will suggest acupuncture/acupressure which I hear is good, but if you're like me the closest practitioner is like an hour away lol.