Based on your symptoms of heartburn (especially if it's occurring while breathing, which could suggest something like acid reflux or another GI issue) and possible black stool (which can indicate upper gastrointestinal bleeding, like from an ulcer or irritation), along with your low
vitamin D (severe deficiency at 5.5 ng/mL) and borderline-low
B12 (240 pg/mL), an upper endoscopy is often recommended in guidelines to evaluate the esophagus, stomach, and duodenum for potential causes.Black or tarry stools are considered an "alarm symptom" that warrants prompt investigation, as they might signal bleeding higher in the digestive tract—dark brown stool is usually less concerning, but if it's truly black and sticky, that's more urgent.
Persistent heartburn also supports this, as it could point to GERD or related complications that need direct visualization.
Your normal cardiac tests (ECG, echo) are good news, ruling out heart problems, and the negative tumor markers (CA125, CA15-3, CEA) reduce cancer concerns, but endoscopy can still help diagnose non-cancer issues like inflammation or absorption problems contributing to your vitamin deficiencies.At age 27 and overweight (BMI around 35, which is obese class I), factors like diet, lifestyle, or even medications could be playing a role—losing weight might help with heartburn long-term. In the meantime, supplement your vitamins as prescribed (e.g., high-dose D3 and B12 if advised), stay hydrated, avoid spicy/fatty foods, and elevate your head while sleeping to ease reflux.Definitely consult a gastroenterologist in Bangalore soon—they can decide if endoscopy is the next step based on a full exam. Places like Manipal Hospital or Apollo have good GI departments. Don't delay if the stool turns clearly black or you notice blood, vomiting, or worsening pain.