I have had a small pus pocket on my left tonsil for 1 month. the only symptom i have is a sore throat. do i need to make a dr apppointment?

Good idea: Suspect that you have lingering infection as viral illness would have cleared by now. However persistent sore throat can also be from tumor. See ENT who could get culture and biopsy if needed.

Highly recommended: It is unusual for a pus pocket along with the symptom of sore throat to persist for a month. Depending on the details of your medical and social history, you may have a bacterial infection that may be contagious (eg. Strept throat, herpes, and others) . Cultures can be taken to confirm the diagnosis. These infections are treatable, and will avoid the issue about getting a biopsy.

Tonsilar pocket: A lot of people mistake tonsilar plugs for pus pockets. They kind of look the same. Pus pockets are associated with tonsilar swelling due to inflammation and redness. If all you have is a white looking pocket but nothing else, it may be normal. Tonsilar epithelium regenerates and creates this kind of appearance due to the fact that the ducts are long and coiled.

Yes: Any time you have a sore throat for more than 2 weeks(as long as there is no fever) you should see an ent. It may be that your tonsils have a slight infection or it could just be post nasal drip. But regardless of the cause one month is too long to put off seeing a doctor.