Hi.. 
Welcome to HEALTHCARE MAGIC..  
I have gone through your query and can understand your concerns..  
As per your complain it seems that burning sensation of the tongue along with white layer over the tongue seems to be due to Yeast or 
fungal infection known as Oral Thrush..
Secondly heartburn and stomach pain seems to be due to GASTRO-ESOPHAGEAL Reflux Disease or acid reflux..
First of all consult an Oral Physician and get evaluated and a thorough clinical evaluation and investigations like microscopic examination of coating from tongue can help in diagnosis..
If Thrush is confirmed antifungal medicines like 
Clotrimazole lozenges, Nystatin mouthwash and Oral Medication like 
Fluconazole can help..
Taking plenty of Probiotics like Yoghurt and Garlic can also help..
For heartburn 
consult a Gastroenterologist and get evaluated and an Endoscopy can help in diagnosis..
For acid reflux Proton pump inhibitor like 
Pantoprazole, antacids and avoiding spicy food can help in resolution..
 Hope this information helps..  
Thanks and regards. 
Dr.Honey Nandwani Arora.