I've noticed today that my youngest kitty Jack, who is a year old, has been visiting the litter box several times today but he's not actually going to the bathroom. He goes through all the motions...squatting and covering up but nothing is there. He doesn't appear to be straining or in any pain. Both times I saw him do this today I stood there and watched to see if he was going so I don't know if he got stage fright when he saw me watching him or if I should be concerned? He doesn't act like he's sick or not feeling well. He's been energetic and playful like he always is. What do you think I should do?