A painful small pimple? on the left surface of my testicle

See your doctor: See your doctor for i &d along with antibiotics as the infection may spread if it is not done.

Confusing statement: Your testicle is enclosed within several layers of tissue in the scrotum, so you will not see a pimple on it.Your scrotum is covered with hair follicles and odor producing glands that can develop abscesses from skin germs.Tiny ones may self heal with moist heat in a few days,but the larger ones would need evaluation & treatment. This might require oral meds but often requires surgical drainage.