What Causes Severe Heartburn?

I am having the worst heartburn pain I have ever experienced. I took a pill before I went to bed and for the last 2 hours now the heartburn has not subsided. I have taken 4 tums and recently a Priolsec OTC. The only relief comes from drinking water or milk. When I do the pain gets worse for a second and then lessens for 10-30 seconds of relief before the pain comes back. My guess would be severe heartburn or Esophagitis.