This sounds like your reflux coming back and going higher into your throat. If tums stops then it is acid.
The back and throat pain are common with gerd I have been fighting this for almost a year throat pain very often.
I have anxiety also which makes it way worse than it is, these posts have helped a lot. If the tums is stopping it then I wouldn't worry about it being anything other than acid reflux.
I would suggest spend some time reading these posts, maybe that will calm your anxiety which might calm the symptoms