I agree with the previous posts, that you need to see your GP. If the pain is severe then you need to go to hospital. Sounds drastic, but if it is something severe like a stomach/duodenal ulcer then you may need an operation. OK, it's worst case scenario, but it's a possiblitly.
At the moment, it sounds like you need a gastroscopy, where they pass a thin tube down your throat into your stomach, allowing the operator to visualise your oespohagus and stomach. Sounds horrible, but not as bad as people realise.
Alternatively, it may be something relatively simple that can be treated with Lanzoprazole (Losec) or Ranitidine. there is no point on reaching for something like Gaviscon as Rennie's are not helping. If you are really not keen on going to the GP, then you can buy Ranitidine at your chemist and try that for a week.
However, given the severity of the pain and discomfort you are experiencing, I'd suggest getting a medical review.
Hope you get it resolved soon. Good luck!