I have been having the same concern I'm 26 weeks due Aug 16 and my baby's movement isn't the same anymore he moves less than before I have a doc appointment Thursday I figured I should ask her what's going on
if your at all worried you really do need to get baby checked out the majority of time its nothing but there are times when it isnt, you should never waste time in getting bub checked out, sudden loss of movement is just a concern as what your describing, anytime you notice a decrease in movement that concerns you, get bub checked out
I'm 24w, I had same issue and was concerned until my doctor visit where I heard baby heart beat was normal. Since the doc visit, baby has been flipping around, quicking so hard and often that everybody wonders, including daddy who can now see my belly jump from outside. Just be patient and only call your doc if absolutely no movement in the next week. Good luck!
I'd call your doctor (or local l&d department) and just see what they may want you to do.