What can cause me to have painless muscle spasms in my neck next to my esophagus?

2 possibilities: Painless muscle spasm involving the crico-esophageal sphincter can be cause by high reflux of stomach acid, so called LPR (laryngo-pharyngeal reflux) or sometimes anxiety. The bottom line is there is a cause for this muscle spasm. You must find out whether or not you have reflux or is this a manifestation of muscle hyperactivity related to anxiety. These are two possibilities.