I'm always cracking my neck to relieve some muscle tension, probably for over 10 or 15 years now. Every once in a while I'll get some severe upper shoulder back pain that takes a while to correct itself, usually getting much better after popping/cracking/traction of some sort on the spine. I'm sure there are probably other people on here who have the same issues in one way or another, and are frequently cracking their back/neck. So I'd have to ask, has anyone ever seen "stars" (a number of black dots that move leaving distorted trails in your vision) after cracking their neck?