Your far enough along to where you should be paying attention to your baby's activity. If things don't feel right it's best to call your doctor or just go and get checked out. Better safe than sorry! If you choose not to go to the hospital or want to contact your doctor first I would have a snack or something to eat (maybe even something with some sugar in it), something cold to drink (I've even had a small glass of coke or Pepsi so get baby moving) lay on your left side and start doing your kick counts. If baby doesn't perk up a bit or wake up by then I would let the doctor know or just head in and let the hospital staff know. Like I said you're already in your third trimester and its better to have your mind at ease! Good luck mama and keep us posted!
I would at the very least call my doctor. You should be fine but its better to be safe and check.