I have a grinding noise at the base of my skull?

I've noticed recently that when I move my head side to side I can hear a soft grinding in the back of my skull. I can often hear noises from the back of my skull, especially when I have headaches, like soft crackling noises or occasional popping. All of this was most recently called to my attention last night when I was trying to sleep and could not find a comfortable way to rest my head on the pillow because it hurt my head. I had an awful headache and my lower back was hurting me terribly. So, I got up and stretched, at 1:00 in the morning... geez... hoping that would help, and that's when I noticed the grinding in the back of my neck. I can also hear this same noise when I move my shoulders back and forth... but that doesn't cause me headaches :P. Normally I would shake this off, thinking that noise and the headaches I have are two separate matters, but I just needed to be sure. Through the years I've had a few seizures, but my last seizure happened about four years ago. I had CAT scans, ENGs, and XRays done, but they couldn't find what caused them. Altogether I've had about five seizures through the course of fourteen years, and I'm only eighteen. What worries me is that, before having these seizures, I usually had a headache. So, it still worries me when I'm driving and have a headache. So. Are these headaches just normal tension headaches? Do I need to worry about the popping noises and sounds?