Mic pics up game audio but not any input audio

So I'm having this issue where when I'm playing I am getting this really poor quality sound of whatever I'm doing on my computer at the time but the mic on my headset is not picking up any type of noise from outside. It doesn't pick up anything I say so my teammates cant hear me and all they hear is my game. I have the mic plugged into the line in on the motherboard through an aux splitter. Any insight onto this situation would be extremely helpful.