38 weeks. Discharge?

I'm 38 weeks pregnant and everytime I go to the bathroom I have a white discharge in my undies. When I went to the Dr I was 1cm dilated. Is the white discharge a sign of dialting more? Part or musuc plug? I also feel very antsy, my heart is racing, I feel like I can get enough air to breath. My legs and arm are sore. I'm having severe back pain and what feels like period cramps and a lot of pressure when I walk, I didn't have any of this with my first pregnancy. So ready to have this baby!! :(