What are some causes for random sharp stabbing testicular pain?ultrasound was clear. history of kidney stones and severe kidney infection.

Kidney stones: Often the pain from kidney stones can be referred to the testicles. In a person with a history of kidney stones and testicular pain, i would be concerned for recurrent stones.

Testis pain: Most cases of pain in the testicle will resolve on their own. I would see your primary care doctor to make sure you don't have an infection first. A scrotal ultrasound may also be helpful. I would advise that if your symptoms persist longer than three months, you should probably see an urologist.