I Noticed My 8 Year Old Daughter Has Been Tilting

I noticed My 8 year old daughter has been tilting her neck side to front and side to side over the last few months. This weekend we noticed the back of her neck was swollen and we took her to pediatrian today who did X-rays. The. X-rays were fine but showed swelling in the skin above the c7. She says her neck feels tights. She does not have fever or pain. What should I do next as her pediatrician is not sure what is wrong.