I tested my saliva and found out its 6.0 ph most of the time and it is the lowest around 5.5 ph in the morning when I wake up , when eating it raises to 7.0 ph. I experimented with different diets during several months (such as 80% fruit, vegetables; 20% protein, carbohydrate containing food) however, ph of saliva remains the same level about 6.0. Also I noticed it has smell like vinegar. I had several cavities in teeth recently and I think this is the reason because my oral hygiene is good. What is wrong with me?