Pressure/Discomfort in Lower Back/ Kidneys when laying down?

Hello, I am a 20 year old male and for the past day and a half, I have been feeling some slight pressure/discomfort in my lower back on either side of the spine. It doesn't feel like its on the surface and it doesn't feel like its my spine. Instead, it feels like maybe my kidneys?

Also, I have been noticing that some of my stool has a greenish color to it for the past 3 days.

Can someone please help me out here?

[jac92007]

This is only while laying on my back, when I roll to either side or my stomach, I do not have this problem.