Litter box problems?

Mitu, my 7 month kitten found a new hanging spot. THE LITTER BOX. Now I want to find out if is a medical problem and I have to go to the doctor right away or just that he likes it, he's bored.
So a bit of history...he pees about 2-3 a day and poops 1 time.
2 days ago he peed 3 times, and had a bit diarrhea. Yesterday peed 2 times, no poop but at night he started going into the litter box, I tought he wants to go but no, he would talk, he would lay in it, he would play a bit. I took him out and played with him but after a couple of minutes he would run back there. He didn't try to pee or poop, he was just there. Now this morning again to the litter box but just for pee and poop, he didn't have problems going. After I cleaned it he went there again but just for a check up and that was it. Now hes just playing and trying to sleep.
Should I worry about his litter box hang out spot?
Im thinking about urinary infection, could that happen and what should I look for?
Ohh he eats and plays like he usually does but doesn't drink water since I feed him only wet food.
Thank you for your help.

http://www.ehow.com/facts_5314342_cats-play-litter-box.html

your question got me curious, because Matt did it too when i first got him fro the shelter(he doesn't anymore) so i went looking for an answer myself......here's what I found...hope it helps

Thank you I will look into it.