back pain 31w help labour?

31weeks 4days having back pain , I was laying on the couch and suddenly started getting spazims now I'm sitting up and the spazims are gone but I'm getting a ache/pain , it's going from one side to the other to middle and across it all at same time it's the hight of the area between ribs and hips ,, now starting to get pain in my leg as well... is this normal should I be worried? It's nothing Iv never been in labour Bub is dancing up a storm since the pain started ??????