I have an odd sensation between my breasts/center of my chest. almost as if there is something in there. lump in throat also. gas? anxiety?

Lump in throat: What you are describing is most likely anxiety and stress reactions. Try antacids like Tums or Pepcid (famotidine) to see if it makes you feel better. Do meditation and relaxation exercises. Keep a journal to pin point causes of anxiety. See your doctor about cause of your symptoms and anxiety relief.

Could be either, or: Even reflux esophagitis. I suggest seeing your family physician to begin workup. Also if you have ongoing anxiety, psychotherapy is a powerful part of treatment -- as in not relying on the zoloft (sertraline) alone. Lump in throat is common in anxiety as well, but people have been known to have both anxiety and reflux.