I am having the same problem my nurse told me to eat something sweet, chew on ice or drink something cold to try to get the baby a little more active. As babies grow and change so do their movements so there may be days where they move a lot then the next day not much at all. If you dont feel the baby move within the next 24 hours you should call your doctor.
Drink something really cold or some juice and lay down. If your busy or your mind is thinking of other things sometimes the baby is moving you just don't realize it. If it doesn't work call your doctor or go into the hospital just to be sure.