Excess mucous immediately when eating solid food.

I have completed my chemotherapy for esophageal cancer.  Tumor was located at bottom of esophageal.  Chemo was successful in that the tumor no longer appears in a CScan.  However I had an endoscopy biopsy that shows cancer remains in the area.  When I eat any solid food, I get hiccups and mucous starts flowing so much that I must quit eating.  Mucous is clear but very stringy and collects in the throat.  I can't even swallow water and my throat feels tight when this happens.
I need to gain weight but this prevents me from getting enough calories to do so.  I am only successful at being on a liquid diet such as meats and veggies being blended with broth to a liquid consistancy.   A liquid diet is very boring.
For several years my submandibular glands have been swollen and feel like grapes when massaged.  Lately I have tried massaging them and the swelling does diminish but returns later.  My oncologist says I do not have an infection and he couldn't explain why the glands are swollen.   Can you suggest possible causes (and cure) of my excess mucous and/or if it might be related to my salivary glands?  Thanks.