I would be more concerned with the rubber allergy you have mentioned, that sounds more likely to be the main reason for your throat restriction.
I am having a few problems at the moment giving the doc reason to think I could have an esohageal cancer or a maybe just an infection, will know more when tests come back.
If it gives you any comfort none of your symptoms match mine except for the difficulty swallowing but normally with a cancer in the esophageus the pain is much lower than you describe.
I'm no expert though or I wouldn't have asked questions on here myself....
Have you had blood tests done since this problem with your throat occured?
Does your doc know about the allergy?
Have you mentioned that the zantac and PPI's are not working anymore?
I would have thought all these need sorting out.
Keep us up to date because you are obviously distressed and worried about the worst case scenario, but try not to.