I am 4 weeks and one day pregnant. (Woohoo!) This is my first pregnancy. I've had mild cramps in my back and lower abdomen off and on for the last 3 days. They don't last very long 5 mins- 30 mins at a time but feel similar to period cramps but less painful. I have taken a pregnancy test every day since Saturday and the lines keep getting darker and I've had no blood or spotting at all. Is this normal? What causes this? Should I be concerned?