lg not staying cold?

i have a under counter lg fridge that is only a few yrs old. i have notice over the weekend that it does'nt seem to be staying cold and the hole that lets the water droplets out was blocked up. i have unblocked the hole and it still not holding the coldness. i got it on 6, one away from the top. i have tried it on diff settings and that does not help it. i have left it over night and one minute it seems to be going icey on the back and then in the next couple of mintues it gone all watery. what could be wrong with it?