I am finding myself in the same boat. I didn't know what was going on either as it started as a small pain that felt like a pulled muscle or something of the sort. Then one day the pain seemed to get worse and by the evening it was so bad I could barley walk! I am in my 37th week as well. I went to the hospital and just to be in the safe side they tested me for a bladder infection and put me on amoxil for the safety of the baby until the results came in. If you haven't had this done maybe you should just to be on the safe side. Anyways, it turned out there was no infection and it is a stretched or pulled muscle brought on by baby growth and packing the extra weight. The doc said to try stay off my feet as mush as possible. What I find helps when the pain gets so bad that walking is excrutiating... a hot soak in the tub. It seems to relax the muscles some. Also, last night I tried sleeping so that my leg was straight as much as possible (rather than scrunched up in a ball as I have been sleeping). It seemed to make the pain less excruciating in the morning when I had to stand up. The pain is still there and I imagine it will be until I deliver, but these things seem to help a little in making the pain less horrible and more tolerable for a bit anyways. Good luck.