Thank you for your query..
1. You are suffering from Gastritis
and Acid reflux
2. The brownish black colored reflux may be due to denatured blood, which is seen with severe gastritis.
3. Hence you should get an opinion from a Gastroenterologist as soon as possible. Medication will help control your symptoms.
4. The warm or hot feeling is usually due to vasovagal stimulation secondary to gastritis.
5. You should avoid energy drinks which contain high calories, high amounts of caffeine, taurine
among other ingredients.