For about a year I've been having neck problems. Late Jan/Early feb I went to go see a PT and they told me to stretch my neck using three exercises. I do admit that it is my fault that my neck still hurts (havent been excercising those neck muscles... only when it is needed). Because of this neck problem, I can sometimes have trouble sleeping. A couple of days ago, I've been noticing a crack/popping sound in the back of my head after I had turned my head to the left and back forward. It doesnt hurt, but the sound is really irritating. I think that I am the only one who can hear it. This was after stretching my neck is when I started noticing it. Also, when I do the stretches (only on left side hurts), ive been experiencing numbness/tingly feeling on my first three digits.... this happens only when I stretch. What's the popping sound in my neck? Is it serious? The numbness feeling?