1. Likely due to processing of medication, pesticides, food additives, environmental toxins by the liver - i.e. making new samll stones.
2. Yes, add unrefined salt to your food, important for balanced stomach secretions, fluid balance,and cell nutrition. It should always be dissolved in the juice of veggies or when cooking rice, etc. Adding it afterwards makes it difficult to be utilized.
3. If you feel OK with it, no problem. Lemon is usually well tolerated by Pittas, whereas most other sour foods are not.
Yes, the pain in the breast is due the distress in the stomach and its meridian that passes through the breast. It is better to avoid that food item.