What causes a feeling of pressure where the sternum meets the collarbone? right in the center at the base of the neck. pcp says heart ok.

Heartburn: For you, two likely candidates. It may be your heartburn. You are on a medicine for this, but maybe it is not controlling it adequately. Look at your diet, consider increasing to twice a day (pantoprazole) for a few days. If not that, maybe it is anxiety acting up (lump in the throat) and maybe your zoloft (sertraline) is not at the proper dose.