7yr old has congestion for 3 weeks no other symptoms, dr prescr. antibiotics, does he need it? no physical exam was done. no fever, no sore throat.

Cold or allergies?: Sometimes a viral respiratory infection can result in persistent congestion. Also the possibility of mild allergies. if the congestion is not causing any problems with sleep and there is no significant coughing, you could continue to watch. I would not use the antibiotics without an exam that could justify their need. A short course of claritin or nasal saline something that you could try.

Nasal congestion: You are asking us to second guess the doctor to whom you took your child because of his symptoms. If you are not happy with your experience at this doctor, it is better to seek a second opinion and talk to the doctor at the time of the visit, especially if you are not happy with the exam and the prescribed treatment.