I'm depressed and sometimes when I get really sad I feel a sudden, sharp, severe pain in my testicles for a split second. Why does this happen?

Ouch! Ur body speaks. Testicles signify courage & boldness. Could be a metaphor of lost courage & fear of moving forward...U mention severe depression... Physical symptoms may be a manifestation of underlying psychological dilemmas; explore those in therapy like u do dreams & meditate on what ur psyche may be trying to say; also, I would consult with md @ any rec tests. Be intrigued, explore&listen to ur body! G luck!
Possible. Chronic testicular pain (orchialgia) is common and well recognized but its pathophysiology is poorly understood. Currently treatment is largely empirical. This article aims to present an overview of its prevalence, possible aetiology and the available treatment options. The contribution of psychological factors is unclear, although some of these patients are depressed.