Why Is My Partially Erupted Wisdom Tooth Gray, Painful, And Possibly Decaying Before Fully Growing In?

Hi, my wisdom teeth are growing in and I can see the top of the one on the bottom of side of my mouth. I m having lots of pain and the tooth has an almost gray color to it and appears to be maybe even in early stages of decaying, but it hasn t even fit grown in yet. Why might this be happening?