Nvidia GT 555m - huge fps drop

When I play video games my graphics card is only at 25% usage. Before this started I had a stable FPS of 60 or 80 in one game. Now I'm getting 20 or so fps on these graphics settings. Even on super low my fps is bad. The odd thing is even on the lowest setting where I could usually get a little over 100 fps it's still at 20-30. My GPU is an Nvidia GT 555m.