When Eating I Often Get Extreme Pain In My Chest

When eating I often get extreme pain in my chest area, and excessive saliva. The pain and saliva last usually about 5-10 minutes. Most recently I get a few painful hiccups during these episodes? I have been tested and they can't seem to find anything? I've had an endoscopy which showed everything is fine? What then would be causing this? I do not suffer from heartburn? I would really love to find a solution to this problem.
Thank you.