If you are sick, visiting a doctor is never a bad idea. There is always the chance they can help you recover faster, and even if they cannot, they can at least confirm that you are simply dealing with a nasty case of the common cold rather than fighting the beginning stages of pneumonia.
When you visit the doctor, you are visiting someone you trust to be able to help you. As such, you need to listen to their advice. If the doctor tells you that there is nothing they can do to help you, there is no cure for the common cold, you need to accept that. Do not badger them for antibiotics or pills that will do you no good against a minor viral infection.
If you do have a bacterial infection, you need to use the antibiotics as they are prescribed. That means, you cannot take twice as much in order to try and kill the infection faster. You also cannot stop taking the antibiotics when you start feeling better. You need to finish the course of medication. Otherwise, you risk leaving behind a small group of bacteria that can multiple, make you sick again and, because they survive the first round of antibiotics, may now be immune to that medication.