For a gum infection you should see a dentist or a periodontist.
A periodontist is a dentist that specializes in gum disease.
A general doctor is not the best to see for gum infections as they are not equipped to diagnose and treat gum infections or other gum problems.
Dentists on the other hand are trained to treat and diagnose a wide range of dental issues including gum infections and gum disease.
A periodontist is a specialized dentist that focuses more specifically on diagnosis, treatment and prevention of gum disease, gum infections and related conditions.
If you have any signs of a gum infection like red, swollen or bleeding gums you should schedule and appointment with your dentist or a periodontist as soon as possible.
Intervening early is crucial for preventing the progression of gum infections and gum disease and other potential complications.
Your dentist may also refer you to a periodontist if the gum infection or gum disease requires any specialized treatment.
If you go to a regular doctor for a gum infection they might take a look but will tell you to visit a dentist or periodontist for diagnoses and treatment.