Bad Breath. Lost my self confidence.

Hello, I am suffering from Bad Breath since 2-3 years. I have noticed the following things but im not sure and have no idea what to do next. 1. Frequent irritation in the upper throat and Nasal Drip 24*7. 2.Tiny black spots on the side of my tongue spread around small area. 3.White coat in the middle and far part of the tongue,also few lumps on the far back. 4. Root canal done to Left-Lower Molar teeth 2 years back, cap replaced 6 months back still when i put my fingers I get a little White Gel like thing which smells bad. 5. I'm having 3 caps for my 3 front upper teeth in which 1 cap has no teeth inside, i can say hollow. When I blow the air through this part I can smell the bad air. * Endoscopy done last year. Result - Absolutely no problem *No Smoking , No alcohol,Less Meat consumption, Tried Oil pulling, Using Mouthwash, Betadine Gargle. Still the same :/ Please help me, almost lost my self confidence.