i've had this happen to me as well.. sometimes they can change positions and start whacking somehwere where we can't quite feel. EG, He/she might have flipped and be punching at your placenta, which you might not be able to feel much.
Try the red cordial and keep an eye on it, definately keep your ob informed! And good on you for being so intune with what your little one is up to in there!!
xx