I have an occasional itch on my testicles. what could be the cause?

"jock itch": The most plausible answer would be "tinea cruris" commonly known as 'jock-itch', which is a common fungal infection, tha is easily treated. See your dr. And a proper diagnosis can be made with the resultant proper treatment. Good luck.

Infection/inflammatn: There are many possible causes- most commonly infection or inflammation. Fungal infxn can develop from heat/moisture int his area (jock itch). The fact that it comes and goes makes worrisome infection less likely. Conditions like crabs, scabies, gonorrhea /chlamydia are also possible. If there is a rash associated w/ the itch than inflammation of skin is possible. Best to be eval by your dr.