I've had reoccuring heartburn and it seems that no pill is helping. i am not stressed and try to eat healthy. what reasons are there?

Choice of foods : Assuming you are otherwise healthy - keep a food and symptom diary. Log when you have symptoms and try to connect it to foods. Most common are spicy foods, tomato sauce (acidic foods), caffeine and many others. Try a little detective work to see what you are sensitive to. If it does not improve it may be time to see a doctor to evaluate. There are many factors to consider.

GERD: Yu probably have gerd, which comes from an in of the musce at the bottom of your esophagus.Appropriate relaxation.

Many possible: Gastro esophageal reflux disease = gerd. Some gastroesophageal reflux (ger) is normal. It becomes a disease(gerd) when it causes organ damage (inflammation of the esophagus, stricture, dysfunction, aspiration, barrett's esophagus, etc…), has adverse impact on you, or requires chronic medication to control. http://goo.gl/0rrqv.

Need endoscopy: Sometimes the issues involved are unresponsive to medication. These include hiatal hernia and ulcer. Generally when symptoms of heartburn to not respond to adequate medications, an upper endoscopy is necessary to confirm the anatomic issue causing the sensation of heartburn.