Maybe we can guide you better if you could answer a few more questions :
How long has your husband been experiencing this pain?? Pain in the esophagus
means he feels pain in the throat or is it in the chest?? If there are no other symptoms accompanying with this pain and it is very recent then it could simply be pharyngitis
due to some infection. And if it is not continuous pain, but related to food intake then it could as well just be an acid reflux
. I think you should see your physician and get it examined.