Hi, if the pain doesn't get better in a couple weeks, you should see a doctor and try to have an MRI done. It sounds like you might have pulled or torn a muscle OR herniated a disc in the neck area of your spine, especially with hearing a "pop". Many people describe hearing and/or feeling a popping sensation when discs herniate. X- Rays pretty much only show the bone in there, they cannot distinguish any soft tissue, hence why an MRI would be better. You certainly don't want to keep doing exercises until you find out what's wrong or you might end up doing more damage. For the time being, you might want to try icing the area first, then use moist heating pads over the area. That might help calm any muscle spasms. Also try taking some over the counter anti-inflammatories, such as ibuprofen or aleve. If none of that helps and you don't feel the area getting better, definitely see a doctor. If it's a herniation , you especially don't want to fool around with that if it's in your neck area! Find out what it is first, then take it from there with the doctor. I wish you luck & hope you feel better soon.