Burden

something that is carried : load.

If you describe a problem or a responsibility as a burden, you mean that it causes someone a lot of difficulty, worry, or hard work. The developing countries bear the burden of an enormous external debt

Something that weighs you down. Usually a worry or a sore point you don't share with close friends or orangutangs. You can also be a burden on someone else when you try and talk about your problems and worries to someone else.