Feeding issue

So I've gotten my ksb for about 4 days now and its 3 months old. I tried feeding it today and the pet store told me that it has upgraded to a large pinkie, so i tried feeding it to him in a tupperware container with air holes and i tried both covered and not covered. It's still not eating, it hasn't eaten for about 2 weeks now and I'm getting a little worried. He pokes the pinkie around but doesn't bite it or anything, he'd push it around the container and try and escape the container. Basically I'm guessing hes playing with his food... Should i be worried about this? and oh, last time he got his weight checked he was 20g and about 11 inches. Thanks

oh and if anybody can post up a picture of how they set up their feeding areas, it'd be really helpful ^^ thanks~

You've only had him for 4 days - it is too soon to be worried.
Sometimes snakes take some time to settle in (especially if they are being messed with more than they like). Now is the time for you to step back & make sure that you have everything right (temperature, cage set up, etc). Is your snake possibly preparing to shed? Many snakes will not eat during ecdysis (though many will).
If you are going to use a separate feeding area (I am not a proponent of that practice, but that doesn't make it wrong), you might try moving the snake and letting him sit there for a while before offering food. A piece of paper towel that can serve as cover might help, too

Thank you so much, i know im a bit noob when it comes to snakes. If i wasnt to feed it in a seperate feeding area, how would i be able to feed it in its cage? because many people told me to put it in a seperate feeding area. Well the average temperature for the cage is around 25-30C and i try to keep it around the same temperature during night time. I also have a heating pad on the bottom of the cage, the cage is covered in aspen with the water dish on the cool side, away from the heating pad. Oh and theres a rock filled with moist moss..sometimes he likes to go in there. Oh its a 10 gallon aquarium with aspen. Oh would it be a good idea to try and feed the snake again this sunday? since i got it last saturday.

Thanks a bunch