Recently I have seen some discoloration on the side of my teeth, especially back towards my molars. However, I do not feel any pain, aches, or sensitivity. Is it a cavity? I am not sure what I should be looking for if I have a cavity.
I have gone through your question and I can understand your concern. Yes, if it is brown or black that means it is in the initial stage of the cavity. It takes a year or two to start symptoms like sensitivity or lodging of food in these cavities. You need to keep your teeth clean through brushing twice daily. If you can upload a picture here so that I can tell you that if there is any immediate treatment or filling needed. The proper way to address the problem is to get a dental filling done (restoration).