17 weeks, and baby moved down?

I'm 17 weeks and 3 days. Well I've been having cramping on and off since yesterday, they feel almost exactly like period cramps.. just not as intense. Well I thought it was just everything stretching in there! I just used my fetal doppler and it seems as if my baby has maybe moved down a little bit! I could always find her heartbeat right around my navel, well now its about 2 inches below my navel! I'm worried because the cramps are coming about where she's sitting! Is this normal or should I be worried?