Sounds like your frog was acting very active at night--that should not concern you unless some enclosure parameter is off (temperature, humidity, hydration, substrate, etc.), but I would double check all those parameter just to be sure. Regarding to the crickets, which I assume you ordered the 6-week crickets, are close to the end of their life circles, thus are starting to die. That back leg seizure means the cricket is dying and losing its mobility. Keeping the cricket tank clean, providing warmth and food will ensure longer lives of crickets.