Hi. Noted the history of your boyfriend having dull pain in the left testicle. This started a few weeks ago, and becoming bothersome. He can t actually touch the pain so he s not sure if it s really his testicle or deeper within his body and just in that area. No burning,itching,discharge,redness ,frequent urination or swelling so far,just that dull ache. Could it be his prostate? The only way to get a proper diagnosis is to get a clinical evaluation and examination by a General Surgeon or Urologist for proper palpation and to conduct the tests. Ultrasonography of the abdomen and with color doppler of the scrotum . These will give the idea about hte probable diagnosis and proper treatment then can be planned.