Penis shaft discomfort? What are the possible treatments if I see the doctor?

See urologist. Depends on the cause. Penile pain can be caused by infections, urethral scar, stones, peyronie's disease, trauma, so the treatment varies.
Depends on cause. Antibiotics if u have a urinary infection or std associated with urethritis. Pyridium, which turns urine orange and alleviates symptoms of burning or discomfort. Urologist might suggest cystoscopy/urethroscopy if some urethral pathology such as a diverticulum is suspected. Possible early peyronie's disease. Treatment depends upon extent and your urologist. Vitamin e, potaba, injections or surgery.