sorry. i was not able to edit my posts...
additional info:
i just try to play food with him. and usually when i have something in my hand ( food ) he will try to jump and grab it. he just tryed and failed.
he jump up not even a inch, and stop jumping. then turn to sit-down mode .
also, he just try to chase me to. after few seconds. he started to limp. but went back to normal after that.. then limp. just changes every 3 seconds.