Thanks for your query.Based on the facts that you have posted it appears that you have pain in left Testis and the Urologist
whom you have consulted had doubt of pain to be due to Torsion of the testis which was ruled out by color Doppler study
This pain and swelling is most likely to be due to Infection of the testis (Orchitis
Please do not worry at all There is no possibility of testicular cancer
Please take some antibiotics like Augmentin
along with some anti inflammatory medication like Diclofenac
for a week after getting prescription of drugs from your family Physician.