Go for scaling and polishing. No toothpaste can remove yellow stains. For cavities

If you see cavity on your tooth, then get them treated properly. Because slowly they may lead to more deeper cavities.

In this matter don't use colgate visible white it causes more sensitivity, so you can use colgate sensitive plus And painout gel for instant relief, and visit nearest dental clinic, go for xray and if it is not involved pulp then you will fill with dental restoration.

Hello, Yellowish teeth are considered as normal colour of teeth in asian race. If you want white teeth bleaching is the option. The black whole can be a developing cavity. If you feel your teeth are not cleaned properly get a scaling done, brush twice daily. You can consult me directly with pictures of your cavity and tooth so that we can properly diagnose it and Carry treatment further.

Visit dentist for further clinical examination & treatment accordingly.